Yes, exactly. Essentially remaking an existing piece to store something inside of it.

Ideally, I’d love to stick to FOSS.

My “goal” would be to design something that can get me rough specs, have a friend use a printer to make some non-metal ones to test out and fine tune, then contact some folks to see if they’d make it in a shop setting.

But that’s frankly very down the line. I’d want to have a very strong product before doing that.