The inner hub is supported by the 6 flexible spokes connected to the outer hexagonal ring. As you grasp the inner hub between your thumb and middle finger and rotate the outer ring with your index finger, the tips of the spokes trip over little nubs in the hub, producing a very satisfying CLICK. (The guts are shown in the cross-section image.)
Print in PLA for a crisp click, and use a 0.4mm line width for optimal printing.
The author marked this model as their own original creation.