This holder can be mounted on the back of a cordless screwdriver. The bits are held by magnets which are located inside the 3d printed part, also the nut for the screw is located inside the part.

To insert the nut and magnets, the print must be paused before the placeholders are closed by the upper layer. I added a filament-change at those positions (M600 gcode command) and then replaced the M600 command by the following commands:

M300;                   beepG1 X10.000 Y200.000 E0; parking position, push forward the bedM1;                     user stopG28 Y;                  home y if you need to remove some filament from nozzleM105;                   return to current temp

Since the magnets are pulled out of the holes by the metal parts of the nozzle, I fixed them with a drop of super glue.

The nut used is an M5 nut (4 mm thick).
The screw used is an M5x20.
The magnets used have a diameter of 6 mm and a thickness of 3 mm.