Black plastic bags from paper are now getting used for 4x5" film holders. 120 spools (why DO I save those?) are great for putting string on so it can be carried in a backpack when camping and not get strung all over other stuff in the pack. Cut a slot in one edge and it will hold the end of the string pretty well most of the time. Paper backing from 120 - I was saving that and will probably save some now as an added assurance against light leaks at the edge of the Dark Room door; staple it on the outer edge on the hinge side and the inside edge on all 4 sides. Might be ugly, but I'm into 'effective and cheap' rather than 'pretty and useless'. 35mm canisters - useful for all kinds of things; scent bombs for deer hunting, lures for trapping, putting interesting things in that I find in the forest that I want to take with me and not crush, small fishing lures, etc. Oh, and they make an impressive conversation piece when someone not into photography sees a box full of them.