While seeking out interesting mechanical fidget toy mechanisms I decided to adapt a Geneva drive into a fidget-friendly design. Geneva drives translate continuous rotational motion into intermittent/incremental rotary motion; you're probably most familiar with them from their use in clocks and in old film projectors. It's a really neat mechanism and a lot of fun to watch and interact with.

I feel this works well as an initial design, but I already know I'll be revisiting it down the line to make improvements.