This paper presents the development of a tendon-driven continuum robot segment with a modular design, simple construction and significant lifting capabilities. The segment features a continuous flexible core combined with rigid interlocking vertebrae evenly distributed along its length. This design allows bending in two degrees of freedom while minimising torsional movement. The segment is actuated by two antagonistic tendon pairs, each of which is driven by a single geared DC motor. Modularity is achieved by embedding these motors in one end of the segment, avoiding the need for a bulky actuation unit and allowing variable numbers of segments to be connected. The design features a large hollow central bore which could be used as a vacuum channel for suction-assisted gripping or to allow ingress and egress of fluids. The design process goes through four iterations, the final two of which are subjected to quantitative experiments to evaluate workspace, lifting capabilities and torsional rigidity. All iterations are fabricated using multi-material 3D printing, which allows the entire structure to be printed as a pre-assembled unit with the rigid vertebrae fused to the flexible core. Assembly is then a simple case of inserting the motors and connecting the tendons. This unconventional manufacturing approach is found to be efficient, effective and relatively cheap.