This is my creation. I am a piercer

Ball Diameter on hoop: 3mm and is affixed on one end
Ball diameter on each end of the horseshoe is 6mm
Hoop Diameter is 12mm

Both of the balls on the horseshoe unscrew.

The inside diameter of the horseshoe is 1/2 inch

You can manipulate the horseshoe with a tool to open it up to a larger diameter.