Are there any APUGers in Arlington VA who have one or two spent 35mm canisters I could pick up? I'm going to make a pinhole camera with my 5 year old and would like to use a spent canister as a take-up reel. I know i could just sacrifice a roll, but I'm really loath to do that.

I'm also open to other recommendation on what to use if there's another good solution.

Thanks,
-Chris