I've been building cameras and shooting pictures in them for about ten years. In the process, I've come up with some interesting camera ideas, and I have many more in sketch journals that I've yet to build.
Perhaps you could describe for us your camera designs. What kind of box, what kind of film holder, shutter mechanism, etc. What is it about certain cameras that seem to work better than others.
As for me, I have a camera that takes 4"x4" paper negatives that are just lovely. The pinhole isn't "ideal"; its a rather thick piece of pie tin aluminum, dimpled thinner, with a pinhole in the dimple. The camera is a small, cubic box, with two wooden dowels poking out the top, which operate two film spools. I cut 8x10 paper into 4x10 strips, which are taped end to end, using painters masking tape, to form a homemade rollfilm. This roll is, in turn, taped to the inside of a long strip of black construction paper. Masking tape squares on the backside are marked with frame numbers, which are viewed through a red window. Think of a 4" wide version of 120 rollfilm; that's the idea.
Another camera I like is a large 12" cube, made of oak plywood. It holds matte board sheets in the box's rear. Slots are cut in the sides of the sheets, alternating, such that a sliding mechanism allows only the front sheet to fall down into the bottom of the box. Paper negatives or sheet film are taped to the front sides of the matte boards. This camera is thus a large format point and shoot. I can load it up with a dozen large negatives, and not be disturbed with carrying heavy, expensive sheet film holders.
I'm currently finishing a more modern looking version of the same idea, in sheet aluminum, that uses a film format of 5x8 (cut from 8x10 sheets of film or paper). The 5x8 format is the easiest way to get the Golden Mean proportion to one's images. This camera I've already tested, and the images are great.
Well, that's three cameras I've described. Hope to hear about yours.