A dovetail mount for the Telrad reflex sight finder. Add 6-32 nuts to the slots near the retaining thumbscrews. If you don't have any metal 6-32 nuts, you can print the included ones.
This is specifically designed to fit the Celestron C102-HD, but should work on others telescopes.
The author marked this model as their own original creation. Imported from Thingiverse.