Worldwide 70-90% of hospitalised patients receive intravenous infusion at some stage during their stay. In many situations, a high degree of infusion accuracy is essential as deviation from the intended dose can quickly become dangerous and moreover costly. Electronic infusion pumps provide the most accurate way of infusion, but they require programming and frequent maintenance. Furthermore, they are unsuitable for austere environments, costly, and could even become scarce in times of a pandemic. Gravity infusion combined with a drop counter could pose an interesting alternative. However, this method appears to be inaccurate over time and setting an accurate flow rate is challenging. The typically used flow regulator, a roller clamp, is the cause of these complications. This study aimed to design and develop a precise and accurate manually controlled over-line flow regulator for gravity-driven infusion. The design process consisted out of three design phases: analysis, synthesis and evaluation. During the analysis, the design requirements were set up. The synthesis phase consisted of generating a morphological overview and several pincher experiments. A pincher is used to clamp the tubing to regulate the flow rate. Then, promising partial solutions were selected, and through rapid prototyping, a final design and prototype were developed. In the evaluation phase, the flow regulator prototype was evaluated based on the set requirements. The developed DropAdjust prototype demonstrated a major performance increase in terms of mean flow rate accuracy and regulation control compared to the roller clamp. In conclusion, the DropAdjust satisfies all tested design criteria and outperformed the roller clamp in terms of accuracy and precision. Moreover, it even showed a mean flow rate accuracy error comparable to the infusion pumps. Thus, the DropAdjust combined with a drop counter provides a more affordable and accessible alternative to the infusion pumps. The prototype is already practice-ready, but several steps are still needed to realise a market-ready device. For instance, conducting endurance tests and acquiring injection moulding advice from an experienced specialist are advised. Also, additional tests are necessary to verify its safety and functionality to qualify for a CE marking.