Well, on this particular thread, we're talking about someone wanting to register relatively tiny 120 film images for sake of masking purposes, which is quite different than how graphics folks would register big sheets and use big punches in relation to taping them together over a light box. I have that kind of big stuff myself, but it rarely comes into play, since I enlarge most of my images. I did do some tricolor "assembly" printing experiments via dye transfer, but would need another lifetime or two to perfect that, let alone fiddle with something like tricolor carbon. I already have more than enough to do with my remaining time.
All my current masking work is done with either Condit micro-pin gear or matching accessories I made myself, and pertains to film originals all the way from 35mm film up to 8x10 film. I also have made quite a number of precision duplicates and internegs which required extremely accurate registration of multiple sheet of film, so I'm very glad I invested up front, quite early, in some top end Condit micro-pin equipment.