Simple fidget button that spins a gear making a satisfying Click sound. It's completely print-in-place and all you need to make it work is a common 4mm diametre pen spring. There is also no glue needed, as it's all press-to-fit.

I added a window so you are able to look at the gear spinning while pressing the button. It's designed for right-handed people, but you can just flip it around in case you want to use it with your left hand.