Cube to experience with thread inserts.
Models for M3 and M4 inserts.

The inserts work great and can take a lot of force.
I was not able to pull them out.
Great fit.
Very tough screw connection

Works both with FFM and SLA Printers.
Tested with Prusa White PLA on Prusa Mini.
Tested with Prusa Grey Tough Resin on Prusa SL1.

Print instructions

Use Prusa Slicer.
Align cube model on print bed.
Closed side of cube should face print bed.
Print.