I second what Rick suggested, get the holiday popcorn tin. You can almost fit a full sheet of 11x14 in it. You can use magnets if you want, but the curl of the paper will hold it too. A curved image plane will give you less fall off than a flat one. Oatmeal canisters aren't what they used to be, they have these plastic tops that you have to tape all to hell to make it light tight, and you have to paint the inside of the whole thing completely. The metal can holds up better and is easier to load and unload. Don't bother with the tripod, just get a brick.