I couldn't find a ring clamp on here so I made one. This was built for M3 bolts and nuts. I'll include the step file if you want to resize.

The wife was sick of the shower caddy sliding down. ;)

Print instructions

I printed the green on its side, and the silver against the flat, both worked. The tolerances are tight, but that's fine for me. I used a longer screw to drag the nut into place before using the correct length.