Nowadays, SMT pogo pins produce a much more compact holder, so I figured I could put all those batteries to good use:
Obviously, the battery holder should grow ears to anchor the 14 AWG copper posts and would look better in black PETG:
The battery lead wires get soldered to the ends of the pogo pins and are recessed into the slot in the end of the fixture. I used clear epoxy to anchor everything in place.
Fits perfectly and works fine!
The OpenSCAD source code as a GitHub Gist: