Integrating electronics with highly custom 3D designs for the physical fabrication of interactive prototypes is traditionally cumbersome and requires numerous iterations of manual assembly and debugging. With the new capabilities of 3D printers, combining electronic design and 3D modeling workfows can lower the barrier for achieving interactive functionality or iterating on the overall design. We present ModElec—an interactive design tool that enables the coordinated expression of
electronic and physical design intent by allowing designers to integrate 3D-printable circuits with 3D forms. With ModElec, the user can arrange electronic parts in a 3D body, modify the model design with embedded circuits updated, and preview the auto-generated 3D traces that can be directly printed with a multi-material-based 3D printer. We demonstrate the potential of ModElec with four example applications, from a set of game controls to reconfigurable devices. Further, the tool was reported as easy to use through a preliminary evaluation with eight designers.