Designed for use with a ¼ inch screw:

I suggest using a strong/tough material. AT LEAST PETG-CF. Use 4 walls with 50+% rectilinear infill.

If you are doing something that requires a lot of motion, use the stronger variant of the male clip. Otherwise, I suggest the weaker clip as it makes camera removal easier.

I have attached STEP files for your modification and adaptation for your custom use case. There is also an example clip for backpack straps that are 80mm in width. Use M3 heatset inserts and machine screws to attach. Also print with a strong material

This has been designed to not come loose over time, or disconnect by itself, but i am still not responsible for your camera if it breaks :-) use with caution!

Keep in mind that using a filament with an additive such as carbon fibre will make the fit tighter
 

Weaker clip (notches at base of flexure):


Stronger clip (no notches at base of flexure)

Designed for a secure connection:

Left image in thumbnail photo is not mine. I have not recieved my camera back yet. I will update the photo as soon as I can.

Step file: