Arlington VA: 35mm canisters for takeup role on pinhole camera

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

If you have a 1hour film processing place such as a drug store nearby I suggest dropping in and nicely asking if they have any 35mm cassettes that they would be throwing away. They usually have the ends left sticking out a bit, just enough for you to tape on your film leader securely if you cut it straight.