Summary

I got cheap 'quick-release' plate from ebay (looks at the attached picture to know what to search for) and I took the bolt out from it. Removed the 'wing' handle from the bolt (so no I have to use big flat screwdriver or coin to screw it into a camera). Then screwed the bolt inside camera, which makes the bolt to stick out and then that can be used to hold the camera on my belt.

The design is parametric so it be adjusted, but by default it's designed to be tight. I think it's easier for somebody to sand/file it down to exact dimensions for few mins to the right dimension than having to tweak stuff in SolidWorks.

The release movement can be as tight or as lose as desired (depending on the sanding).

The brass inserts are M3 threads and I inserted them with help of a soldering iron.

See video of it being in action:
https://youtu.be/1WtkuZS2Mak