I made this to go with my Star Projector.
I wanted a design I could glue down on one side, and attach an LED to on the other side, so I made this threadable CR2032 battery holder based on NotSoSolid's Design, to which I did a complete remodel to get the topology doing what I needed it to.
After the first accident where I couldn't get the battery out, I've added a rectangular escape hole, the battery sits very snugly in there.
You will need a little bit of wire to thread the electronics through.
There's also an indent for a very faint 4-pin LED, but you can ignore that if you wish :)
Just print it up on its side (as given), no supports needed.