Remixed this with inspiration from WRW87 design found here.
For my drill and printer the hex holder slots were super tight and the support block against the battery prevented the battery from coming off.
I opened up the slots to give a tight friction fit and changed the shape and location of the support block on the battery side to allow more space for it to slide.
Note: This will not work with short bits the holder is too deep to be useful.

For my printer the friction is just shy of too tight, figure the slot would wear a bit with use.
I also added a 4th slot because if I was rebuilding it from scratch I figured why not.
It attaches with a M4x6mm socket head cap or socket button cap screw