This is a Finder Scope Ring set with a standard dovetail. I made this for my Celestron 9x50, that has an external diameter of 53mm. Should work ok for any mount of the same size. It uses the stock o-ring that I unfortunately forgot to measure.

Is to be assembled with M5 nuts and knurled screws, or maybe 5/32", but I haven't checked.

I used infill 35% that gives a nice rigidity for supporting auto-guiding.

New design with less parts, single print: https://www.thingiverse.com/thing:5442940

Also see for the guiding camera case: https://www.thingiverse.com/thing:4485282

Don't need fine alignment (for a guider scope)? https://www.thingiverse.com/thing:5442933