4mm bit to 1/4" hex shank

thingiverse

**** If you make it and it works, please click like :) **** The picture says it all. I have at least two dead mini cordless screwdrivers. Both died because the tiny metal gears stripped out. But the bits are still good. Why not put them to good use? Print this adapter at 100 percent infill. make sure you use a brim to keep it adhered to your print bed. Keep in mind, don't expect this to handle too much torque or it will snap. If you find it isn't strong enough, you could try to print it on it's side but I have no idea if it will work. Regardless, it is worth a shot.