The present work is the result of a five-month graduation project on the topic of Large-Scale Additive Manufacturing and its potential for added value creation in the preservation of architectural heritage.
The project is made up of two distinct sections prefaced by a short introduction that contextualizes Large-Scale AM within heritage preservation. The first section dives into the theoretical principles behind each discipline, setting the groundwork for a later, more in-depth analysis of their needs and opportunities. This is done through a series of case studies on first, Adaptive Reuse projects (Adaptive Reuse being a sub-discipline of preservation), and second, Large-Scale AM projects. The AR case studies help to understand other designers and architects’ approaches to Adaptive Reuse, while the LSAM case studies are used to extract a series of features unique to Large-Scale Additive Manufacturing that present potential for added value creation in a preservation project. This section concludes with the mapping of these features to the 3D printing principles that enable them, as well as a series of factors that affect the potential success of Adaptive Reuse projects.
The second section aims to apply this theoretical framework to a real-world case. In it, a site is chosen based on a series of suggestions resulting from the earlier part of the research. The site is then visited and analyzed in an effort to understand its cultural, historical, and architectural significance. The results of this analysis are condensed into a series of design inputs that inform the design of an intervention which proposes the revamping of the site. Finally, the intervention is designed and broken down into its core principles, concluding with a reflection on the potential of Large-Scale AM in the preservation field.

The Halo frame is a medical device used to provide cranial and cervical immobilisation for patients with severe spinal injuries. It ensures proper alignment of the spine during healing by stabilising the head and neck through a combination of a halo ring attached to the skull and a vest worn on the torso. While the device is effective, its acceptance among patients and healthcare professionals has been limited.

This lack of acceptance is largely due to the unaesthetic appearance of the frame, which can have a negative psychological impact on patients, along with issues related to comfort, bulkiness, and the difficulty of assembly and adjustment. These factors often discourage patients and doctors from opting for the device, despite its clinical benefits.

The redesigned Halo frame addresses these challenges with a focus on improving aesthetic appeal, comfort, and usability. The new design minimises visual intrusion by using only two vertical rods and an additional set of horizontal rods extending over the shoulders, moving much of the structure behind the head. Carbon fibre rods and a medical-grade plastic vest were incorporated to significantly reduce the weight while maintaining structural strength. Adjustability has been enhanced with a rack-and-pinion mechanism, allowing precise height adjustments even when the patient is lying down. The design also reduces the bulk of the frame and improves the fit, ensuring it accommodates a wide range of body types.

Allowing controlled micromovements in the redesigned Halo frame supports healing by promoting natural bone stimulation, which prevents weakening over time. Research shows complete immobilisation can inhibit recovery, as seen in other orthopaedic devices like knee braces. The frame balances stability and small movements to enhance the healing process while ensuring safety.

Finite Element Analysis (FEA) was conducted to evaluate how deformation in the frame translates to deformation in the spine. Boundary conditions from existing research were used to assess whether the design meets safety and performance requirements, confirming its viability as a medical device. In the re-design, it was determined that the maximum angular displacement in the vertebrae is 6.1 degrees, and the maximum horizontal displacement between two vertebrae is 1.2 mm, confirming the design’s safety and performance.

User feedback played a significant role in refining the design. Orthopaedic technicians and design students provided valuable insights, leading to improvements such as increased adjustability of the horizontal rods and optimised hinge placement for greater accessibility. Additional considerations, such as developing reusable components and enhancing the frame’s visual appeal, aim to increase patient acceptance and sustainability.

Finally, this report outlines key recommendations for further development, including advanced performance testing under dynamic loads, prototyping with actual materials, and focused user studies to refine aesthetic appeal. Early collaboration with manufacturers is emphasised to ensure the design is cost-effective and feasible for production. Finally, steps toward MDR certification are detailed to prepare the product for market introduction.

This research explores the possibilities of combining additive manufacturing and weaving of textiles to create a novel textile-form. In recent years, additive manufacturing has revolutionized manufacturing processes by enabling the creation of complex three dimensional geometries with precision. Conversely, weaving, a traditional method of fabric production, offers inherent structural integrity and flexibility. However, recent research focusses on developing three dimensional textiles. By combining these two production methods, this research unlocks new opportunities for the production of composite textiles with enhanced properties and functionalities. During the FDM-printing process yarns were placed like a warp between two layers of filament. This basic principle of integrating these processes in explored in this research.

Throughout three design phases, the process was explored and further developed. Subsequently, the material underwent characterization through two rounds of testing. During the first tinkering phase, emphasis was placed on the connection points between the yarn and the filament. Achieving a connection between both materials heavily depended on the height of the nozzle. Various combinations of materials yielded samples with diverse behaviours, ranging from flowy to more elastic and springy textiles. All the samples exhibited anisotropic behaviour: along the x-axis, the material could plead like a textile, while along the y-axis, the filament provided rigidity, allowing the textile to form a dome. In the second phase, the emphasis shifted towards exploring forms by experimenting with various printing patterns. By implementing a zigzag pattern, an auxetic textile was successfully produced. When the samples were pulled along the x-axis, the material demonstrated the ability to open up in the z-direction. An experiential characterisation test was done by using the Ma2E4 toolkit, which conformed the curiosity and surprising qualities of the material. However, the material’s weakness and fragility posed limitations on the freedom to explore its potential fully. Interesting to find out was the contrast of interpretation between manufactured and handcrafted. During the third phase of tinkering, greater control over the auxetic behaviour of the material was achieved through experimentation with different densities and the implementation of cutting the yarns with a hot nozzle. Also the textileness was increased by using LW-PLA and adding noise to the print. For the technical characterization, a tensile test was conducted, revealing the clear anisotropy in the strength of the material. Additionally, the consistency in print quality was confirmed.

For this novel process and material, a variety of future applications could be envisioned. Ranging from utilizing the material’s movement in the z-direction for isolation to its ability to open up for light control. The process enables a seamless transition between a solid plastic and a textile, opening possibilities for applications such as shoes or chairs.

This research project delves into the potentials of material jetting printing through an exploration of voxel printing techniques that integrate solids and liquids. The focus centers on assessing the shock absorption (SA) capabilities of diverse samples incorporating varying materials and printing patterns. The key materials employed in this investigation comprise Agilus, a flexible substance, and Veroclear, a rigid material. The project advances through multiple phases, commencing with an extensive literature review and culminating in the successful fabrication of a range of varied samples.

The research objectives encompass two main aspects. Firstly, the goal is to generate a series of test samples characterized by distinct attributes, facilitating a comprehensive evaluation of their shock absorption abilities. This entails manipulating factors like material composition and printing patterns to yield a diverse array of samples. Secondly, leveraging the test outcomes, the aim is to conceptualize a product that effectively demonstrates the potential of material printing technology. This product will exemplify optimized shock absorption characteristics, serving as a tangible illustration of the technology’s possible applications. In this design process, the diverse assortment of test samples and their individual traits are considered, leveraging these findings to craft an inventive and practical wearable product.

The realization of these objectives initiates with an understanding of a material printing apparatus equipped for voxel printing. Thorough research is undertaken to amass pertinent information concerning voxel printing methods, material attributes, and shock absorption principles. Armed with a solid knowledge foundation, the project progresses to the printing phase, wherein an array of samples is produced employing rigid, flexible, and liquid materials. Meticulous attention is dedicated to selecting printing patterns, enabling a comprehensive exploration of the impact of different geometries on shock absorption.

The subsequent stage encompasses subjecting the printed samples to controlled shock tests. This examination aims to discern patterns, correlations, and trends that can inform future design choices. Drawing from these findings, a proposal outlining future projects capitalizing on voxel printing technology is formulated. This proposal takes the form of a conceptual project designed to effectively showcase the material’s capabilities. Ultimately, this research endeavors to stimulate the development of ingenious and efficacious applications of voxel printing, thereby contributing to the advancement of materials engineering and product design domains, exemplified through a conceptual wearable product that serves as a reference for the potential utilization of the technology.

Eighty percent of women after mastectomy wear an external breast prosthesis either permanently or during the period before breast reconstruction. External breast prostheses replace the removed breast and aim to recreate the original body shape. However, while each woman has a different chest wall and scar topology, most commonly used are standard commercial prostheses, which often fail to provide comfort and symmetry to the wearer.

Given the risks and costs associated with elective reconstruction surgery, women who decide to use external breast prostheses should be offered options that are as well developed as their surgical alternatives.

This project envisions an external breast prosthesis design method that allows the efficient manufacture of personalized forms. 3D scanning and 3D printing are suitable techniques to create solutions tailored to each person’s necessities. 3D scanning allows having a digital twin of the chest wall topology that helps create the geometry that perfectly matches an individual woman. 3D printing, on the other hand, eases the fabrication of patient-specific products. For this reason, this project considers 3D printing as a suitable technology for the production of personalized external breast prostheses.

Research has been conducted with breast care experts and women after mastectomy to explore the pain points associated with existing external breast prostheses, which helped identify several design opportunities. This project aims to achieve a specific main goal: To provide a realistic consistency of external breast prostheses to touch. Current solutions tend to be too stiff and hard, which makes them uncomfortable for the user.

Polyjet 3D printing offers the possibility to print with rigid, flexible, liquid, and gel-like materials. Furthermore, owing to the droplet-based working principle of this technology, it is currently possible to mix different materials with full control of the proportions and the design of the material distribution droplet by droplet. This allows achieving a mixture that works as a homogeneous material at a macroscopic scale and having tailored mechanical properties. This project approaches the challenge of external breast prosthesis redesign by exploring the possibilities and limitations of voxel-based Polyjet 3D printing; specifically, the different mixtures of liquid and gel-like materials encapsulated in an outer cover made with flexible material.

Extensive prototyping is performed throughout the project and compression tests are conducted to obtain quantitative data regarding the softness of prototypes and its similarity to a natural breast. Besides the objective information obtained from these tests, a user evaluation is conducted with ten participants to compare the objective data with human perception, which is ultimately more relevant for this topic due to the subjective nature of tactile experiences.

This thesis investigates novel foaming materials for fused deposition modelling (FDM) which have been introduced in 2019. The materials are able to foam by the addition of foaming agents. Foaming materials for FDM printing can be advantageous since they can create lightweight models, and have good impact strength and toughness in relation to their weight (Nofar et al, 2022). The goals of this thesis are to: research the existing knowledge about foaming materials for FDM printing, characterize the different printing parameters that influence the amount of foaming and propose an application for foaming materials for FDM printing. The investigated materials are foaming PLA, ASA, and TPU.
The first goal is reached by conducting a literature review. First, the material properties of foaming materials outside the scope of FDM printing are investigated to better understand the advantages for foaming materials for FDM as well. Second, printing parameters are investigated to understand how these affect final printed products. Third, the available literature for the foaming filaments for FDM printing is investigated. An overview of the material properties in tension is made for the foaming filaments. This shows that most material properties are known for the foaming PLA.
The second goal is reached by conducting three experiments, which investigate the influence of nozzle temperature, fan, printing speed and flow rate. From these experiments it is concluded that the nozzle temperature, printing speed and flow rate influence the expansion of the material, depending on the desired outcome. The fan speed only influences the expansion of the foaming TPU. With the results of these experiments, an overview is made of the influence of the printing parameters on the expansion using the three-link chain model (Doubrovski et al, 2011).
The third goal is reached by conducting a compression experiment in which the foaming PLA is compared with expanded polystyrene (EPS). The results from this experiment and the printing parameters are applied within a motorcycle helmet as demonstrator. This demonstrator shows that the foaming materials for FDM printing could be an interesting area for further research.
This thesis provides a starting point for further research into the influence of printing parameters for foaming materials, as well as the material properties of the foaming filaments. It is recommended to further investigate the influence of more printing parameters on foaming, such as bed temperature, nozzle geometry and type of printer. Second, it is recommended to further investigate the material properties of foaming TPU and ASA as well, since only PLA was tested in the compression experiment. Apart from this, the materials could also be further investigated for tension. Lastly, the proposed foaming PLA sample for the motorcycle helmet could be further investigated for higher strain rates, to confirm the feasibility for the use of motorcycle helmets.
Overall, this thesis investigates the printing parameters for foaming materials which are used to create samples with specific densities for a compression experiment. With the found printing parameters and results from the compression test, a helmet demonstrator is create

In the field of 3D printing, Multi Material Additive Manufacturing (MMAM) has gained substantial recognition, as it offers interesting new possibilities. MMAM allows the combination of diverse polymers to create products with enhanced, composite properties. However, a significant challenge emerges when chemically incompatible polymers are combined within this technique, which complicates recyclability. This research addresses the issue of connecting these polymers while preserving strength, durability, and the capacity for disconnection, which facilitates efficient recycling at the end of a product’s life cycle.

Polymers, while versatile and widely used, often prove to be chemically incompatible due to their distinct chemical compositions and inherent characteristics. This incompatibility becomes a major bottleneck in the field of MMAM, as it obstructs the effective adhesion of polymers to each other. The result is products that are exceedingly challenging to recycle, perpetuating a long-standing issue in the 3D printing domain. Conventional industry solutions, primarily reliant on mechanical interlocking methods, lack the necessary flexibility for disassembly, rendering the materials inseparable and hindering recycling. This issue has long hampered the establishment of a sustainable 3D printing ecosystem.

To conquer this challenge, this research introduces the “Z-pin” connection, a novel reversible interlocking method. The Z-pin method serves as a bridge connecting chemically incompatible polymers and offers an approach that exceeds current alternatives. The introduction of the Z-pin’s design helps the joining of different polymers while still facilitating their clean separation when necessary.

The Z-pin method is most novel in its remarkable capacity for disconnection. By subjecting the polymer connection to controlled heating, within a range of 60 to 95 degrees Celsius, this method facilitates the simple, clean, and efficient separation of materials. Most notably, this process can be executed with basic tools and, in certain scenarios, by manual disassembly.

The developmental process of the Z-pin method comprised three phases. The first phase involved the initial design and evaluation of a range of connection methods. Two methods that demonstrated great potential were selected for further refinement in the second phase. Here, an optimisation process took place, including geometry, print parameters, and material properties. The third phase was dedicated to implementing the enhancements identified in phase two, culminating in a comprehensive and finalized design. This iterative methodology addressed the extensive range of possibilities uncovered during preliminary research.

The research affirms the performance of the Z-pin method over conventional solutions, including the hacksaw and alternating layer methods. The Z-pin method has an impressive tensile strength, positioning it as a contender within the MMAM domain. Furthermore, its straightforward geometry affords scalability and adaptability, enabling it to meet the specific prerequisites of a diverse array of applications.

In the field of soft robotics, rigid joints and links are replaced by soft, deformable elements, This causes soft continuum robot arms to excel in unpredictable environments, but to face challenges during control and shape reconstruction. The sensing ability present in octopus suckers provides inspiration for solutions. Octopuses employ their suckers not only to strengthen their grasp but also as tactile sensors to control the shape and position of their soft arms. This has motivated researchers to integrate artificial sensorized suckers in soft continuum robot arms Although various sensorized suckers have already been developed, their employed sensing methods tend to be low in resolution and are often poorly embedded into the overall sucker architecture. In this work, these limits are overcome by presenting an octopus-inspired suction cup with integrated high-resolution tactile sensing abilities. This is achieved by utilizing the Chromatouch Principle, which relies on embedding colored markers in the suction cup membrane. Tracking these markers with a camera produced tactile images containing useful information about forces, deformations and interactions with objects. Fabrication with multi-material additive manufacturing enabled direct integration of these markers into the suction cup membranes. We demonstrated the design’s basic functionality by conducting pull-off and pickup tests. The design exhibited a normal pull-off force of 9.53 N and a shear pull-off force of 5.28 N. It was also able to successfully pick up both flat and curved objects. The sensing ability was showcased by training a Convolutional Neural Network to learn the relationship between the camera images and the orientation of the suction cup with respect to a touching substrate. Using a spherical coordinate system, the orientation could be predicted with an error of less than 2 degrees for latitude and less than 9 degrees for longitude. This performance was validated by using the trained network to successfully correct the orientation when picking up objects under an angle. For a single suction cup, this ability can be utilized to correct the orientation and achieve perpendicular contact with an object, crucial for achieving a seal. On a larger scale, the integration of multiple suction cups in soft continuum robot arms has the potential to form a representation of the arm shape as a whole. It can thereby contribute to overcoming the control challenges faced in the field of soft robotics.

This thesis presents the development of guidance cards for consumers engaged in “3D Printing for Repair” (3DPfR). When being engaged in 3DPfR, consumers face multiple challenges, for example printing parts that can resist high temperatures, or making parts with fine details. The goal of this project was to develop guidelines which allow repairers to overcome these challenges themselves, this way allowing them to repair a broader scope of products and to increase their chance of success. This thesis consists of three parts, each presenting a distinctive phase of the project.

During the first phase of the project, literature research was performed to study the concept of repair, the discipline of 3DPfR, the related disciplines of “Design for Repair” (DfR) and “Design for Additive Manufacturing” (DfAM), and 3D printing categories and technologies. Several usable frameworks for both 3DPfR and DfAM were identified. Despite the similar name, it was found that the knowledge on DfR is of limited use to 3DPfR as defined in this project. Additionally, it was found that there is a strong focus on desktop Fused Deposition Modeling (FDM) in 3DPfR, while it was also demonstrated that several other printing technologies are available to the user as well, mostly through 3D printing service providers. Lastly, user interviews were hosted, from which it appeared that the interviewees were unaware of many of the insights acquired in the other chapters of this part, affirming the need for supporting tools.

The second phase focused on acquiring new insight in the challenges encountered during 3DPfR. The acquired knowledge from Part 1 was applied in a case study. In this study, a Dyson V11 vacuum cleaner was disassembled and mapped. A variety of parts with different challenges for 3DPfR was selected, after which the parts were redesigned and printed in metals and plastics. Through this study, it was found that the current set of criteria to determine the eligibility of a part for 3DPfR was not complete. Also, ways of (partially) resolving the challenges in 3DPfR were acquired, as well as a more profound understanding of the difficulty imposed by the challenges.

The synthesis of the accumulated knowledge of phase 1 and 2 took place in the third phase. In the final phase of the project, guidance cards were developed, with each of the cards addressing one challenge in 3DPfR. The cards include an indication of the difficulty of designing and making the part, an example, an explanation of the limitations, and finally strategies for designing and making the part. The cards were evaluated with several users and generally received positively, each participant indicated that the cards would help him or her to repair more products through 3DPfR.

Magnetic Soft (shape memory) Materials (MSM for short) are a form of shape memory hybrid in which the shape change is initiated by magnetic particles embedded in an elastomer matrix. When an external magnetic field is applied, these magnetized particles will align themselves to this magnetic field, straining the elastomer in a specific shape. Once the magnetic field is removed, the elastic properties of the elastomer pull the object back to its original shape.
This report describes the work done on the development of a 4D printer, in which the shape change of the MSM objects is programmed during manufacturing by controlling the orientation of the pre-magnetized particles in the still uncured silicone. An external dual extrusion system is used to mix a two component silicone during 4D printing, so that the material cures upon hitting the build plate, while staying liquid during printing. The goal of developing a reliable system capable of extruding and printing the highly viscose magnetic material was however not achieved, as the extrusion motors lacked the needed force and the system was not rigid enough to deal with the high pressures involved. Adoption of a new printer design in which the path from extruder to build plate is severely limited is recommended.
In addition, a literature review has been conducted into applications of generic shape memory materials (SMM), metamaterials and magnetic soft materials with the purpose to draw inspiration from proposed applications of these materials for a novel MSM application design. It was found that MSM applications showed many overlaps with SMM and metamaterials, but that there were also some gaps in the reported application proposals of MSM where SMM and metamaterials are currently used for. MSM could be a valuable material used for (haptic) communication and texture change. More (indirect) relations with MSM, SMM and metamaterials have been identified which could serve as inspiration for future projects.
Lastly, a novel demonstrator concept design has been developed that shows the unique fast and multi-directional characteristics of MSM, using the findings of the literature review and the use of the Material Driven Design method. With additional input from peer students in a workshop, the idea of a 3-way changing texture is proposed. This texture utilizes specific magnetization patterns in an array of MSM actuators to generate two texture variations depending on the direction of the applied magnetic field, in addition to a neutral state when the field is removed. Its feasibility is proven by small scale prototypes.
This project has been the second time this material has been researched at the Faculty of Industrial Design Engineering at the Delft University of Technology, building upon previously delivered work and paves a path for further iterations on manufacturing and design of applications of the magnetic soft material.

3D printing is currently blooming in a lot of different industries, including fashion in the form of 3D printing onto textiles. In parallel, fashion circularity is an increasing movement that has emerged due to the negative impact that fashion creates on the life on this planet and the planet itself. Therefore, a shift to responsible consumption and production methods (sustainable development goal 12) is necessary. To join this circularity movement, 3D printing onto textiles for fashion is required to fulfil certain requirements, including recycling. However, recycling is nowadays hindered by the lack of methods to separate the 3D printed structures from the textile at the End of Life (EoL). This graduation project researches the possibilities to achieve material separation at the EoL, so that the materials can be independently recycled and turned into new products.

The contribution of this research is a framework to achieve material separation that enables recycling for interfaces created by 3D printing onto textiles. This framework has three key steps, which are: developing a separation plan, selecting materials and designing the polymer-textile connection. The separation happens through heat deformation and more specifically, through increasing the temperature locally during separation. The selected materials are PLA, as the polymer, and plain-woven cotton, as the textile. The printing method used is Fused Deposition Modelling (FDM). The connection design is implemented on a product application, which is a footwear’s mid-sole bond to the upper shoe’s textile. Four interface designs are tested on separation conditions related to EoL and a scenario of usage conditions, to investigate the effect of the connection design on separation and thereafter, recycling. At the end of the research, clean material separation between polymer and textile is achieved, which is a promising achievement for reversible 3D printing onto textiles.

This research project departs from two novel concepts, 3D printing fluid, and
fluidic interfaces.

With polyjet 3D printing, micro-droplets of different resin materials are ejected in layers and hardened instantly. Through this technology, complex 3D
parts can be manufactured with up to 8 different materials, including flexible and rigid materials. This project departs from a research study in which
a non-curing resin is used for the first time as one of the printed materials
(McCurdy, 2016), which allows for 3D printed fluid geometries to be designed
inside solid parts. However, the effect of fluid printing on the printed part
quality is not mentioned beyond a list of design guidelines.
Fluidic interfaces is a novel concept, in which fluid is visibly displaced
through small channels, as a result of deforming the flexible structure in
which fluid is placed.

The main objective of this project is to discover whether combining the concepts of fluidic interfaces and the opportunity of 3D printing three-dimensional fluid structures, will create new forms of human-product interactions.
Therefore, these two fields are researched, resulting in a haptic controlled
with 3D printed fluid mechanisms.

Fluidic system structure research
Through low fidelity fluidic system prototypes, made from silicone it is
researched how 3D fluidic systems need to be structured for creating new
human-product interaction forms. From this, it is acknowledged that the
design structure opportunities are based on an input (force), displacing the
fluid, and an output (intended result) which can be visual, physical, or the
combination of both.
With the different structure opportunities, a literature exploration is performed into existing developmental research prototypes within the established opportunities achievable with a fluidic system. With these findings,
generated fluidic system ideas are rated in terms of viability, selecting dynamic textures as the idea to be developed into a concept, and demonstrate
the design opportunities of 3D printed fluidic systems.

3D printing with fluid research
During the development of a dynamic texture concept, fluidic samples are
3D printed to observe the impact fluid has on the structural result. The effect
of this is significant, as fluid spills between printed layers (during the print
process), and severely weakens solid structures. In addition, flexible material
printed in contact with fluid will deform greatly. Thus, solutions are exposed
regarding the part printing alignment and the use of support structures to
manufacture successful 3D fluidic structures.
It is anticipated that 3D printed fluidic parts are to be integrated into a concept, based on the deformation resulting from hydraulic pressure. Therefore
an explorative analysis is carried out comparing finite element predictions to
actual test results, creating a model for further mechanism predictions.

Concept design
Dynamic textures is chosen as the idea to be developed into a concept, thus
the visual and tactile elements of texture are researched. As a result, 4 elements can be dynamically altered with a 3D printed fluidic system: surface
colour, surface height, curvature and hardness. With this opportunity, a
haptic feedback controller is selected as the idea to be developed into a final
concept.
Human tactile variables play the role in receiving information from surface
textures, from which fluidic mechanisms are designed. The mechanisms
(roughness sensor and texture actuator), vary the perceivable surface
roughness and height, with the use of deforming flexible membranes. These
mechanisms are tested on three participants to obtain the design guidelines for optimal texture perception.
The final concept is based on the communication between the user and
a product, through varying surface textures. This is tested with a proof of
concept, on three participants concluding that the product opportunities
of this concept lie in the implementation into immersiveness, or creating a
new tactile language, however a longer testing duration will be needed for
this validation.

Venously printed contributes to the field of HCI and digital manufacturing by exploring the scope and possibilities for programmable and responsive fluidic interfaces, using multi-material 3D printing as a manufacturing technique. Novel meta-materials and computational composites have proven to open up new design paradigms and continue to expand the design space for HCI and material design with unprecedented I/O configurations and material experiences. By encoding the computational logic of dynamic and responsive behaviour into the material’s structure and properties, these materials allow shifting away from typical 2D (digital) interfaces towards embedded responsive 3D objects and materials without the need for external logical operators or controllers.

A novel concept within this field is fluidic interfaces, which utilise liquid flow as a medium to drive dynamic appearance triggered by mechanical deformation input such as pressure, twisting or bending. Within this research, multi-material 3D printing is explored as a manufacturing tool for such fluidic interfaces to allow for more complex 3D geometries, dynamic visual output and encoded computational logic. A set of demonstrators are developed with programmable dynamic appearance, showcasing the capabilities of this manufacturing workflow and the possibility of being tuned for specific material experiences or temporal form in interaction design.

To allow for the fabrication of these interfaces Venously printed presents a fabrication pipeline, including a computational design and simulation tool for designers to validate the responsive behaviour and iterate on their design before going into manufacturing. Additionally, a voxel-based support structure for 3D printing complex internal cavities is developed to provide better printing quality as opposed to available workflows whilst still being able to be removed from complex internal structures. Finally, a first step for the characterisation of the experiential qualities of fluidic interfaces has been performed via a set of interviews. This led to promising future applications and material experiences which can be explored in future work.

Fabricating custom-made ocular prostheses is currently a highly-skilled, labour-intense and non-reproducible process performed by an ocularist. Custom-fit prostheses are made from acrylic using a plaster mould, the iris is hand-painted, and veins are mimicked by adding red embroidery threads. Digital production techniques provide opportunities to improve and automate this process. Therefore, this graduation project aims to research a possible digital workflow, including data capturing and calibration, modelling and 3D printing, for producing 3D-printed full-colour ocular prosthetics. The workflow should capture and reproduce the eye’s appearance to create a life-like ocular prosthesis that resembles the patient’s facial appearance as closely as possible.

Research into manual and digital production techniques results in a proposed digital workflow showing how a prosthesis can be produced. The workflow consists of five phases: collect, design, produce, post-process and finalise and shows how the patient and the ocularist are involved.

Data capturing and calibration
The patient’s eye colour data needs to be captured and calibrated to ensure accurate colour reproduction of the eye. The images can be calibrated by applying a colour profile made from a colour target to correct the camera error. The capturing research showed that photographing is a suitable technique to collect colour data for accurate colour reproduction if the eye and the colour target are shot under a controlled light condition. Multiple calibrated iris images were printed and compared to the participant’s eye to review the capturing and calibration process.

Modelling
The modelling research showed that a parametric model based on a computational design template is a suitable solution for adjusting the prosthesis model to a personalised shape.
The template should automatically model the inner parts of the prosthesis based on the outer shape and important parameters, such as the iris and pupil diameter. The first steps towards creating this computational design template are shown in this report by modelling a parametric iris disk.

3D Printing
The full-colour 3D printing technology's capabilities were exploited to reproduce best the various features of a human eye, such as the sclera, blood vessels, pupil, cornea and iris. This investigation showed that mapping an eye image to the model does not always give the desired result and that different printing techniques are suitable for different eye parts. Alternative approaches, like contoning, sclera generator and ‘dotting’ and ‘varying line deepness’ techniques, are exploited and show promising results. However, a voxel-based printing technique is needed to combine and control these approaches, and current software lacks these possibilities.

Two experts and five users validated prostheses produced following the proposed digital workflow through an interview and by photographing them next to their eyes. All participants were impressed by the prosthesis and rated the total prosthesis as ‘sufficient’ or ‘good’. Nonetheless, it remains a challenge to reproduce the exact iris colour, structure and veins. A voxel-based printing technique is recommended to have more control over these various aspects. More research is needed to explore the possibilities for controlling colour on a voxel level and to model a complete voxel-based prosthesis. The comparison between the manual and digital workflow showed that 3D printing results in significant time savings since over four hours of manual work could be replaced by 3D printing. 3D printing ocular prostheses make the workflow reproducible and faster, which leads to more accessible and affordable prostheses in the future.

“3D Printing of Large Objects with PET Flakes” is the Graduation project of Daniël Eikelenboom of the Faculty of Industrial Design Engineering of the TU Delft for the Rotterdam based company 3D Robotprinting. The project focusses on the development and implementation of an ‘all-inclusive’ PET bottle recycling unit containing a large-scale 3D printer as made by 3D Robotprinting and the development of a preliminary set of guidelines for manufacturing products using the 3D printer. The aim is to enable the 3D printer to use PET flakes gained from bottles as feedstock. Therefore, the 3D printer was adapted and guidelines for manufacturing were developed. An iterative approach is followed, in which the exploration of the ‘novel’ source material and defining the design guidelines for manufacturing are at the heart of the project. After defining the context, the 3D printer was analysed and a literature study was performed, from which was concluded that the current polymer extrusion machine is likely too small to process the initial flake sample. With an initial sample of the material, experiments were performed in order to examine directions for a possible solution and to determine the most important properties, like flake material density, particle size distribution and funnel flow behaviour. By increasing the polymer extrusion screw channel depth at the feeding zone to 8 mm and compression ratio to 4:1 (resulting in a screw diameter of 30,4 mm), the 3D printer should be able to process PET flakes with a diameter up to 4 mm. To ensure the material does not contain particles larger than 4 mm in diameter, it should be shredded, granulated with a 3 mm mesh and sifted using a 4 mm sieve consecutively. Using literature of previous experiments, preliminary design guidelines for creating products with the 3D printer from 3D Robotprinting were set up. From a set of ideas gained from context analysis, a children’s slide was chosen to experiment on. Multiple prototyping rounds were done to perfect the slide’s printing performance and to refine the design guidelines. The project’s final results are: • Advised dimensions on the most important part of the system: the polymer extruder. • A list of preliminary design guidelines for optimizing a product for manufacturing on the 3D printer. • A children’s slide showing the application of the design guidelines.

Cephalopods (e.g. squids, octopuses, cuttlefish) are able to actively adapt their appearance in terms of color, texture or transparency. The goal of this project is to mimic this ability with a simple and mechanical solution and apply this technology to a product or environment. This resulted in a pneumatic mechanism which folds open after actuation and thereby changes color. This mechanism was then applied to a wall panel which can be used to cover the inner or outer walls of buildings and thereby change the color of the facade or space.

This graduation report aimed to improve the mechanical properties of a sustainable 3D print material made of microalgae, in order to create an macro-porous 3D structure with enhanced longevity and photosynthetic activity. This research builds upon the alginate based bio-ink from Balasubramanian et al (2021). Their material proposal lacked structural stability and print resolution, which made geometries of more than six layers impossible. Moreover, the bioprints were confined to a nutrient plate. These challenges formed the motivation for the research. The goal for the optimized bioprinting protocol was to make use of the advantages of additive manufacturing, by creating a macro-porous shape with increased surface ratio. The hypothesis was that the microalgae would have more access to light, air and nutrients which would increase oxygen release and carbon dioxide fixation. In a series of explorative studies, in close collaboration with nanobiologists, biomaterial designers and 3D printing experts, a direct ink writing approach was selected to construct the microalgae bioprints. Additional components were added to the alginate bio-ink formulation, which concluded in a material with improved print fidelity and resolution, so that more than 25 layers could be bioprinted. With the optimized protocol, the 3D printed construct could be crosslinked so that the print was stable enough to be handled. The microalgae immobilized in the ink formulation survived more than seven days in the 3D printed geometry. The photosynthetic performance of the material was observed, by building an incubator prototype with oxygen and carbon dioxide sensors. The sensors measured two different bioprints simultaneously, a macro-porous cube and a solid cube. The superiority of the photosynthetic ability of the porous geometry over the solid geometry could not be concluded, due to the limitations of the sensors and the prototype setup. Important insights were found for further research on the improvement of the test setup. The optimized microalgae bio-ink is a valuable material with sustainable benefits. The material can actively fight carbon dioxide pollution, is carbon neutral in production and is biodegradable. The technical optimization of the bio-ink in this study formed the first steps towards a functional living microalgae artefact.

This report shows the development of a method that joins two chemically incompatible materials during Fused Deposition Modelling (FDM). State of the art FDM printers can extrude more than one material during the printing process. Due to chemical incompatibility of many polymers, the selection for combining materials is limited. This gives the following goal: “Generate a method to create a dual material object, made of two chemically incompatible materials during the FDM production process”. Studies related to multi-material FDM printing are discussed to find a starting point of this project. The use of a form interlocking shape to join the two chemically incompatible materials is chosen for further investigation. The concept is a form interlocking shape. This shape consists of rows of bridges made of polylactic acid (PLA, rigid material). Thermoplastic urethane (TPU, flexible material) is extruded under and around these bridges to create an interlocking shape. The PLA bridges are created using a non-planar printing approach. As opposed to the regular FDM process (planar), we created a continuous bead across multiple layers (non-planar). A prosthetic hand is created for demonstrating the method. The PLA main body and phalanges are connected with TPU links to allow bending of the fingers. We focused on the criteria: strength, applicability and process continuity. Based on these criteria, we made design choices regarding form interlocking shape, printing procedure and sequence, size and geometry and slicing software. We created specimens for determining the force-displacement relationship and used the peak force as a measure of the interface performance. The proposed concept (bridge pattern) is tested against two benchmarks: the overlapping feature available in slicer Cura (current industry standard) and an interlocking shape printed using a planar approach. Our proposed concept resulted in a higher peak force than the overlapping feature: 491N compared to 415N, an increase of 18%. The planar interlocking shape resulted in a peak force of 504N, even higher than our proposed concept. This production method is relevant for multi-material products manufactured with FDM. Examples are given of products in robotics and prosthetics, compliant mechanisms and wearables. The prosthetic hand was chosen as a demonstrator. A qualitative evaluation was performed on this prosthetic hand: using manual force only, neither the interface bond or the materials (PLA and TPU) could be broken. We have shown a method that creates a stronger bond (vertical interface) between two chemically incompatible materials (PLA and TPU) than the current industry standard.

The use of 3D printing technology in manufacturing environments has experienced rapid growth. Manufacturers have realised the potential of the technology. 3D printing enables the reduction of costs and lead-times of parts, components and tools used in production processes. Adoption of this technology is facing various challenges. A major challenge is the identification of suitable parts for Additive Manufacturing technology. Assessing a part’s suitability for 3D printing requires a substantial amount of knowledge of 3D printing technology. Within manufacturing and production environments, a limited group of people is trained to do understand the technology. It is expected that the frequency and quality of applications will increase the value that will be added by 3D printing. This development will be driven by the capability to identify new applications. The more stakeholders are educated in this field and understand the technology, the more opportunities will be identified. Given the above, this objective of this research project is to investigate how production line operators can be more actively involved in the initial stages of the 3D printing workflow. Through extensive literature and contextual research, the potential to enable production line operators to identify parts and problems in their section of the facility has been exposed. Various influential opportunities and challenges in their participation have been established. After a round of internal validation of the research insights, a strategic decision was made to focus design efforts on developing a digital platform. The objective of this platform is to enable operators to participate in the relevant steps of the 3D printing workflow. Through an iterative process, an Application Portal has been designed. This portal is a mobile application that supports production line operators in submitting new ideas. In addition to the above, the system offers the following functions:
1.Active collaboration between stakeholders
2.Exchange of project developments insights
3.Validation of application suitability A prototype is developed in Axure. This software is used to validate the concepts with a variety of manufacturing clients, operators and 3D print experts. The applicability of the concept has been validated for a majority of clients. These results illustrate that the solution offers significant value to achieve active participation. Additional design goals have been achieved to a great extent. The application portal provides operators with a tool to express their ideas. They can actively participate in innovation and take ownership of the applications they have identified themselves. Additionally, the platform offers Ultimaker and its manufacturing clients an opportunity to gather relevant data to work towards a future of automated part identification. Inevitably, the prototype has its limitations. However, this study represents a step forward in the acceleration towards accessible part identification by novice users in manufacturing environments.

During this project the possibilities of enriching the functionality of an Ankle Foot Orthosis (AFO) by implementing mechanical metamaterials are researched. The project is executed for Buchrnhornen, a company based in Eindhoven which has over 70 years of experience in manufacturing orthopaedic shoes and orthosis in a traditional way. Mechanical metamaterials are artificial structures with mechanical properties defined by their structure rather than their composition. They consist of rationally designed unit cells with unique mechanical properties. The project focusses on replacing the hinges and stops used in a traditional AFO to block plantar or dorsal flexion by a mechanical metamaterial structure which could achieve the same mechanical functioning. A digital program in Grasshopper (Rhino plug-in) is developed which generates a design space based on an input scan of the patients lower leg. The design space is split up in different parts based on the mechanical requirements of the specific areas in the AFO. For each design space, a suitable topology infill which meets the mechanical requirement of the area is developed and generated. Through an input which can be defined per generated model, mechanical requirements can be customized per patient. The output of the digital program is a ready to 3D print .stl file. An extensive research on 3D print methods and materials is done in order to find the most suitable method to fabricate the generated model. The best option was found in a Composite Fibre Co-extrusion (CFC) printer which is able to implement carbon fibre in a model. The addition of carbon fibre ensures much stronger prints which are able to resist the high forces which are applied on the AFO. The project is finished with a conceptual model generated through the developed digital program as well as an extensive evaluation and advice on the researched print methods and topologies. To conclude the research, a list of generic findings and recommendations for further development within Buchrnhornen is provided.