We present an algorithm to balance 3D printed models using movable embedded masses. As input, the user provides a 3D model together with the desired suspension, standing, and immersion objectives. Our technique then determines the placement and suitable sizing of a set of hollow capsules with embedded metallic spheres, leveraging the resulting multiple centers of mass to simultaneously satisfy the combination of these objectives. To navigate the non-convex design space in a scalable manner, we propose a heuristic that leads to near-optimal solutions when compared to an exhaustive search. Our method enables the design of models with complex and surprising balancing behavior, as we demonstrate with several manufactured examples.
The authors would like to thank Jan Wezel for his help with the 3D printers and his valuable advice on manufacturing matters, Maurizio Nitti for model design, and our colleagues from Disney Research, IGL, and CGL for insightful discussions and support. This work was supported in part by the ERC grant iModel (StG-2012-306877).