Matthias Wandel made this rather tongue-in-cheek invention to help him shake pens.
Using my gear template generator program, I was able to establish that a three-tooth lantern against a mating cycloid shaped gear should just barely work smoothly. I wanted a high gear ratio for my pen centrifuge, so this was a good place to a gear with such a small number of teeth.
I wasn’t completely sure how well it would work, so I made a test gear. Not wanting to waste too much plywood, I only made a segment of a larger gear. The little gear has three “pins”, which are actually small 3/8″ (10 mm) ball bearings. There’s no rubbing on this gear!