Network of perpendicular carbon nanotubes (2x2x2)

I spent time to finish up this structure made of 12 interpenetrating carbon nanotubes (CNTs) last weekend. Compared to the G-surface, this structure is not that complicated. Once one figures out the structure of node that connects three different perpendicular CNTs, the rest is hard work. One should be able to see how the arrangement of heptagons in a node is related to the inner part of a toroidal carbon nanotubes (TNCTs).