A cube of bevel gears. Joint work with Sabetta Matsumoto. Sometimes designs like this are called “brain gears”.

To make this, you will need two copies of the half core, eight copies of the gear and its cap, twelve M2 nuts, four 16mm M2 bolts and eight 12mm M2 bolts.

First, use four of the nuts and the 16mm bolts to bolt the two half cores together. Then slot the remaining eight nuts in the slots in the arms on the core. Then bolt each 12mm bolts through first a cap, then a gear, then into the arm on the core and through the nut in the slot. 

It can be a bit tricky to get the gears lined up properly - it is easier to get the gears lined up properly before bolting them in.