Handle for 1/4" bit holder

Other than a deep hole for ¼" hex tools, there's a reinforcement to assist against the torque: 
you can fit a washer (or small metal plate) inside the handle, this does engage in a slot that you can cut (with a Dremel, or an angle-grinder if you have a steady hand like me). 
Then you just drop some Superglue or other runny adhesive to fix it all.

You want to print this with PA Nylon or PETG/PET using 6-7 wall loops. Avoid using PLA as it would just crumble away.