What's the situation like with Minox cassettes where you live? Here in the UK the supply of plastic cassettes has almost completely dried up. Minox film on ebay reaches high prices. I've got a couple of metal cassettes from MS Hobbies but having some plastic ones for experiments and spares would be really useful. Can't find any anywhere. Is anyone making the plastic cassettes anymore? Anyone got spares they want to sell?
Some places sell replacement Minox cassettes -- either empty of full of film. These are 3D printed and some (NOT all) of them leak light. The leaks are not a problem if you load and unload the camera in a dark place.
Blue Moon Camera in Portland, Oregon, US is the "official" supplier of Minox film, even though they definitely hand slit and load it. That said, I haven't heard of any problem with their supply of (plastic, non-3D printed) cassettes. Not sure where they get them. Might be worth contacting them, anyway. They're good people.