Support-free interior carving for 3D printing

Recent interior carving methods for functional design necessitate a cumbersome cut-and-glue process in fabrication. We propose a method to generate interior voids which not only satisfy the functional purposes but are also support-free during the 3D printing process. We introduce a support-free unit structure for voxelization and derive the wall thicknesses parametrization for continuous optimization. We also design a discrete dithering algorithm to ensure the printability of ghost voxels. The interior voids are iteratively carved by alternating the optimization and dithering. We apply our method to optimize the static and rotational stability, and print various results to evaluate the efficacy.