US Patent 7658464 System for creating a three dimensional printed structure

A system for creating a three dimensional, printed structure comprising a plurality of layers. The system comprises: a plurality of printheads arranged in groups, the printheads in each group being configured to print voxels of material to define a respective layer of the structure, wherein a first portion of the printheads print a structure material forming the structure and wherein a second portion of the printheads print a sacrificial material to thereby form a void in the structure; and a substrate configured to be operatively displaced with respect to each group so that printed voxels from each successive group can form successive layers of the structure upon the substrate.