There is an interesting article on 3D printing of artifacts with a structured, inhomogeneous interior in CAD Journal. A team out of Turkey shows how the interior is decomposed into cells defined by a 3D Voronoi diagram and their sites. The slicing algorithm capitalizes on this coherence and minimizes print head moves that do not deposit material. This approach has been implemented on a client/server architecture that computes the slices on the geometry side. The slices are printed by fused deposition, and are communicated upon demand.