running in circles
This ring has been in my head for a while now. It features two circular tracks with brass bearings trapped inside. They can circle round and round but they cannot come out.
Originally meant to be only one track with two balls, this ring was modeled after the idea of a super-collider. That later evolved into this which is a little more interesting visually, I think.
It is a size 7.75 and is set on a 1/4" wide low dome band.