Summary

The hole for a nut is sized for an m4.

For fit be aware it may vary with your filament.
I printed this in ABS and it was so snug it extended the model by 0.5 mm(contained file is the extended version)

If printing in PLA, the model may need to be shortened slightly due to the differences in shrink rate.

3+ perimeters, high infill recommended

This could be attached to anything with a m4 bolt, I personally drilled a hole in a C-clamp I had and bolted this mount to that.