Ok here is my version of @ThothLoki rotary axis for my eleksmaker a3 diode laser. Mine is designed for a nema 17 and replaces either the x or y axis on your laser. I use t2 laser to convert the lateral movement into rotational movement. You will need to know the diameter of your round surface for that. In the video you will notice I had to put the base on a box. The version included now has a thicker base so this shouldn't be necessary.
List to be updated to exact soon
You need 7 bearings
a hand full of standard bolts (1/4 i think but I'll confirm when I run to home depot next)
a few metric m3 bolts
nema 17 stepper motor
It just fits a 40ml hydroflask in the a3 frame.
All parts have been printed and work on my prusa i3 mk2s in petg. Several need support
If you want to make it better send me a message and I'll send you the fusion links.