Just an amusing anecdote:
A few editions back, Colin Fletcher, in his book "The Complete Walker" (often considered the "Backpackers Bible") listed possible uses for the screw-top film canisters while backpacking, such as to carry: salt tablets, salmon eggs for bait, oil for lube jobs on hair and beard and even boots, not to mention for cooking. Also for carrying odds and ends such as spare flashlight bulbs, sewing kit, water-purifying and vitamin C tablets. The list goes on.
In subsequent editions, Fletcher added a footnote in which he related a story about a court case. Apparently, a young college man was stopped for a traffic violation and the officer spotted a 35mm film canister on the seat. He then proceeded to search the car, based on the fact that these film canisters were commonly used as a "stash" for marijuana, thus he had probable cause to search. The defense attorney cited Mr. Fletcher's book as evidence that 35mm film canisters had MANY uses other than as a drug stash, and won his case.