NEW, as of 19-11-2023:

I recommend printing the TPU version, the rear rack mount has a 6mm hole so I also recommend using M6 + nylon hex nut.

I found the ABS mounts too weak. So I tested with TPU 100% infill, it's really rigid + its unbreakable, survives when bike falls etc.

Also doesn't break when pulling ends apart to fit on the frame.

OLD

Print in ASA or stronger, at least 4 walls and 5 bottom/top layers. M5 bolt + nylon hex nut. Really simple design that just requires one bolt + hexnut to mount your rack.