For really quick cameras I have used 35mm canisters, hunks of soda can, and some electrical tape. Any hour processor can provide a vast amount of canisters. Paper negatives 1.5"x 2" work and are quick and cheap for large groups. My last workshop we made and shot 175 cameras in 3 hrs.(it's that high school teacher training) I live by "cheapo, cheapo, productions"! :-)
Chuck Flagg
