See https://www.thouters.be/Doorhandle.html for more information

I designed this door handle during COVID-19 lockdown after my kids slammed the kitchen door against the radiator a few times, and I had to glue the original a few times. (it's an old door that will be replaced in the future).

WARNING: If customising using OpenScad, I had to postprocess the stl file using Meshlab's
"Filters -> Cleaning and Repairing -> Merge Close Vertices" to be able
to slice this with PrusaSlicer. (Just do import mesh, apply the filter and use export mesh and select STL)

Print the object laying down. I don't use supports for the screw and nut holes, just go through the hole with a 5mm drill to clear any overhang malformations.
Insert M5 nut into the hole, and pull the nut into its place by tightening the screw. have the screw pull against a small bar, like a second screwdriver to avoid its front end pushing into the plastic. Be carfefull not to overtighten, the plastic may crack

I was carefull with infill in the part that mates with the door to avoid cracks there, I used 4 perimeters and more (selective) infill there.