When I was a kid, soda pop cans had tearaway tops that would separate from the cans when opened. There was sort of a ring-shape on one end of that piece. SCA people would collect those by the hundreds or thousands and use them to make mail armor suits and stuff. It looked surprisingly good, and since it was just thin aluminum, was very light. Very good for running around on a hot summer day recreating the Battle of Hastings or whatnot.