Brain gear

A mechanism consisting of a pair of bevel gears for each edge of an octahedron.  Joint work with Sabetta Matsumoto. This design uses bolts for the axles of the gears. 

To make this, you will need two copies of the half core, twelve copies of the gear, fourteen M3 nuts, twelve 35mm M3 bolts and two 10mm M3 bolts.

First, use the 10mm M3 bolts and two nuts to bolt the two half cores together. Then thread each 35mm M3 bolts through two holes in the core and one of the gears. 

You may need to put the last few gears in place at once before inserting their bolts. If you've bolted in eleven of the gears and the twelfth is still sitting on your desk, you will have to backtrack a bit.

I used locknuts for the 35mm bolts, just to make sure that they won't come off.