Slothouber-Graatsma puzzle

This is an easy-to-print version of the Slothouber-Graatsma puzzle.

This deceptively simple packing puzzle is made of:

• Six pieces of proportions 2x2x1
• Three pieces of proportions 1x1x1

The objective is to pack these 9 pieces into a 3x3x3 cube. It is trivially easy once you understand the trick, but it might take a while to get the key idea.

I include a version with 1.5cm x 1.5cm x 1.5cm voxels and the parametric OpenScad file, so you can modify it.