chat I'm looking for keywords/solutions for something 3D printable.
I want to to make a panel with buttons, switches, connectors, ... but I don't want to design it from scratch.
what are these things called? what is already out there?

more details:
imagine the modularity an AV/server-rack, but instead of one <thing> per height, I'm looking at one HU that contains multiple <things>. "like keystone?" yes exactly! just more compact.
I imagine a box where 2 sides are just slots for custom covers

possibility: mount DIN rail, print clips that attach to it, then any box I find can be a "module"

heck, I'd design that box in the slicer directly

with that in mind, any box with a hole in it would work, they can just be attached next to each other