A screwdriver for a regular 1/4" bit-holder. It has a spring locking feature to prevent the bit-holder from falling out. This is not made for short bits: they will plunge into the hole completely. The hexagon hole has a diameter of 1/4" +200µm.
I could not find such a simple thing in my local hardware store. There were only sets consisting of huge screwdrivers and bits. Probably 10€ saved. Welcome to the new world old industry.
Use a huge brim (i.e. 10mm) and print with the hexagonal hole facing upwards. Don't use supports. You may want to use higher infill percentage for higher break resistance. Furthermore in my case black PLA is much stronger than grey PLA.
You may need to push in and pull out the bit holder a few times to smoothen the inner surfaces and allow for easy bit holder removal.