I have got 14"x14" x-ray copy film (AGFA Curix duplicating film) and I thought it's not so much meaning to cut it small to LF cameras, as I learned that its ISO is like print paper (thanks to Peter K).

Instead, I plan to make a pinhole camera for full size of 14"x14" for contact print. I like the size and square format of the film very much.

Now the question is: I remember an early camera design that sheet film stacks are put on the camera back and after exposure one sheet of film is dropped to bottom of the camera for next exposure without having to open the camera in darkroom. I think I have to put black paper on the back of each film. However I can't figure out how to realize this, especially the mechanism which would make only one sheet (exposed) will fall down. I googled to find any schematic that I have seen years ago, but in vain.

I think film flatness is not an issue because it's pinhole, furthermore this film is very thick and rigid by itself and I will back it up with black paper.