I enjoy working with gears and put two spur gears together with a ratchet and a finger ring to make this fidget.  The larger gear rotates the smaller gear at 5X faster.

The finger ring is a press fit into the base.

Using the Fusion 360 spur gear script to design the gears was pretty simple after a couple of trial and errors. 

I used the recent finger tweezer design to help install the retainer rings on the shafts because the retainers are so small.

The clearance between the ring base and the gear base is 0.2 mm. I found that the 0.175 mm clearance was too tight.

I used a 0.3 mm for the shaft to gear clearance.