I just recreated the rear cap for the S series Zenza Bronica Lenses (compatible with S, S2, S2A, EC, EC-TL, EC-TL II cameras).
I successfully tested it with the following lenses:
However, it should work also with other lenses of the same family.
I printed it with the opening facing the plate, because I wanted the three lips to come out well. It works, but it wastes a lot of material for the internal support. You can try to print it the other way, probably if you support correctly the lips it will end up fine too.
I printed mine with PLA, using PETG as support interface, just to be able to clean it up easily.