Some black, spongy-pressed foam around the edges of the box back that corresponds to the non-moving rectangle of the film holders will help with the lighttightness. Pressing the holder against the foam tightly can be done with a dowel rod. Sort of like the Leonardo pinhole cameras. Rosanne
>In addition to using the holders, you'll have to devise a method for >securing them to your camera in a light tight fashion. I build wooden boxes >and use a wood pressure plate sprung with the springy things you get in >metal frame hardware kits.
