Up the resolution of the gear
Fix inner gear thickness

We didn't set rim_thickness, so the teeth were the default size.
Poke 1mm holes in each gear tooth

This allows us to drive in some cut paperclips for shear strength.
Disable the rotation of the inner gear
Move pinholes closer to center
Move pinholes back out again -- they were getting eaten up
Remove setting of $fa.

We get something like 360 facets on the larger circles which drives the printer
crazy.