There are places that have kits for building Eurorack stuff if that’s what you’re talking about… I made a fuzz module and some simple switching modules before…
https://store.synthrotek.com/Modular
Hey..
Yeah it’s directional..
The black stripes should mark the cathode (negative) side…
If you have a multimeter you can test and see which side is which…
But on all didoes I’ve seen, except Russian ones, the stipe(s) mark the cathode…