The original design by Mikek is great, but I don't have much of a selection of M3 cap-head screws. I do have a great selection of M3 flat-head screws! Also, my experience with pressed-in M3 nuts is not great. Heat-set nuts wont fall out, and they have more than double the grip-length.

I modified the original design for use with the M3 3-mm X 5-mm heat-set nut. You will need two. You will also need two M3X8-mm flat head screws. Phillips head screws are shown, but you can class it up with a hex or Torx screw!

Printed version shown was printed in Sunlu ASA at 0.2-mm layer height and 70% fill.

Material, layer height and fill percentage are flexible.