It would be nice to add a few more tiling patterns. This isn't done in the previously described fill routine, which assumes the orientation of the tile is uniform throughout space. The body of the gear was originally filled as a rectangular solid, which was then mapped to a cylinder. This means the structure will be under tension, and not energetically optimal, and it would be good to determine the energy cost of such deformations. If it's too high, the result will be an unstable structure.
Nobody wants gears that fly apart under a load.
I've been tinkering some with filling in hydrogens, which requires enumerating bonds. The result of that, applied to the big gear, is this.