A few notes:
Use ESun matte black PLA + filament printing with a 0.2mm nozzle, and you will get opaque light tight cassettes. Should be some models out there that work. The one you have needs to have the "lobes" moved a few tenths of a mm apart, it's too small. Adjusting the %printing size might help too.
Film drum diameter is fixed, otherwise the image spacing will be wrong. Camera was only intended to make 18 images per roll, and reducing the drum diameter will make them closer together -- much reduction in diameter will result in images touching. I've printed up a few that fit nicely -- the fact that yours don't always seat is due to the drum not fitting down on the points of the driver, either turn the drum a little or slightly advance the camera. Same issue with Kiev carts.
18" of film works great, easy to make something that length to measure out film. More than that will probably jam unless you are using microfilm.
Finding tape that sticks to anything but itself these days is a challange. Scotch won't work on PLA, better on PETg, but the tape Kodak used to hold film onto paper backing seems to be un-available anywhere I can find.