Summary

Another of the space filling polyhedra. http://en.wikipedia.org/wiki/Bitruncated_cubic_honeycomb

Nice in that it can be combined with other polyhedra that have hexagonal faces.

UPDATE: Updated the files with a perfect truncated octahedron. The previous starting TC, which I'd downloaded off of the 3D Warehouse, turned out to be imperfect. Apologies if you tried to stack with it. The current files work.

UPDATE TWO: Added a version with thicker struts.