First of all I want to thank mr_vinn for the model he provided.
This model is suitable for 20 mm straps, I also changed the design of the bars and of course the space for the magnets. For this model I used magnets with nominal size of 6 mm in diameter and 3 mm thickness however, measuring the exact size of my magnets, the magnets were 6.05 mm and 2.63 mm thick, for this reason I designed the space with a diameter of 6.0 mm and a dept of 2.7 mm, thus check the right size of your magnets. Also 6x2.5 or 6x2 mm magnets will fit. You will need a pair of pliers to press the magnets inside the recess, please also add a drop of glue to be sure that the magnets stay put.
Remember to first fit one magnet, then check for the correct orientation of the second magnet ed then install it.
Print with supports (for the bars).
Available file formats .3mf, .f3d, .stl.
The author remixed this model.
Differences of the remix compared to the original design: