So this afternoon while my son was practicing in the backyard with his bow I settled down on the back porch with some cowhorn and a dremel.
I didn't take any step-by-step pictures because I wans't sure it would be worth showing off.
The horn was an atrociously made powder horn I had stashed in a box in the garage for years, and I finally found a use for it. (the hole in the ring is from where an eyelet screw was attached)
I still need to do some final sanding if i decide it meets my exacting standards, if not it goes in a box of lessons learned.
This is my first attempt at a thumb ring made out of anything other than leather, I will most likely attempt to make one out of coin silver in the near future.
I used it a few times and so far I think it's a little too long, but maybe I'm too used to the feel of my leather one. I definitely need more range time with it.