The Szilassi polyhedron is a seven-sided torus where every face is in contact with all of the other faces, proving that for toroidal topology, 7 different colours are required for a surface map.
This simple little shape is a mathematical curiosity, designed to demonstrate colour printing on the sandstone material. It is also a handy filler for topping those orders up to $25.
PLEASE NOTE: Following changes to the minimum size requirements for some materials, this model was no longer printable. Consequently, I have now increased the size of the model from 2.5 cm to 4 cm in order to make it printable again.