I wanted to print this on a resin #d printer but it consumes so much materials and i would like to put in magnet and keychain.

Extra materials needed:
6x3mm magnet
Keychain loop

Glue the magnet inside the bit insert. There is a recess to guide it. It won't be completely bury the magnet so that bit will hit magnet 100% of the time. I made the handle shorter too - as a keychain.

I mod this using the shallow hole (around 1cm-sh deep - magnet will help)