Hi,
I made an adapter Canon lens to 1.25" (31.75 mm). It allows you to mount a 1.25" eye piece or camera behind a Canon camera lens.
I put a M3 insert nut in the hole on the side of the cylinder to tighten the eyepiece with a small M3 screw.
The cylindrical part is quite tight, so maybe you will need to modify the CAD file or file a bit the inner surface. That's why I provide a .step file.
Any feedback will be appreciated
I wish you a clear sky ^^