yeah that sounds interesting... After carting around change bags, paper envelopes for unexposed and exposed 'negs' and having to sit down on the ground to make a neg change (and thats only with a 5x7 camera) I can see your multi-shot design would make life easier and more productive!
your 'roll film' camera is a little like my 1st pinhole... I jammed a 35mm canister into a 100 sheet box of Ilford Ilfospeed (4x5" size... probably tells you how long ago this was.. mid 80's) so that the reel the film winds onto poked out of the box and I could wind it on. Wasn't as smart as yours to be able to tell how far to wind the film on for the next exposure! Several exposures ran into each other! Also, I didn't know anything about sharp pinholes and using tinfoil, etc.. I just poked a hole in the opposing side of the cardboard box! The pictures were primative!
My 5x7 pinhole (which I call A Nigon B57) is made out of some kind of particle board and consists of 3 boxes that fit inside each other. The middle box points the other way to make things light tight and holds the pinhole (soft drink can aluminium) and slides off to allow a new sheet of paper to be inserted. This actually allows the camera to be a zoom-pinhole... about 150mm to 240mm if my memory is correct. I switch the pinholes to suit whatever focal length I'm using. I screw a quick release plate into the bottom of it so it sits on my tripod quite well.
My Nigon B810 (although technically it's a B7.9-10... I didn't allow for the thickness of the material while constructing it) is made of matt board, taped together. It's a single shot unit with a curved focal plane. I think I did that to even out the exposure, but will probably remove that feature due to the distortion it introduces. This camera usualy gets sat on something, with a brick or such object wacked on top to keep it still!
I've been collecting ice cream sticks which I have plans to make a camera out of with a 4x5 DD as a film/paper holder. Just got to eat a few more ice creams