I decided to learn Solidworks, and I didn't like any of the sleeve-style cases on here, so I took some inspiration from a Swiss-Army style SD card holder, and designed my own Switch cartridge holder from scratch. I designed it to be held together with 10-32 bolts and lock-nuts, because I have a lot of old skateboard hardware laying around. This is the first iteration of this design, I'm sure I'll refine it more in the future.
My printer is pretty old, so some of the edges on my sample print are a little rough, but with a better printer, I'm sure the finish quality will be a lot better.
You can stack as many of these together as you need to hold all your games. The top and bottom piece are the same, so there's only 2 different parts. You can also use this as a keychain if you just print the holder. The games stay in the frame pretty well. If you like this design, check back for future iterations.