My first experience with "production methods" cost me 25 cents and came as a child. In the days before the third rail, you could clamber down to your local subway or railroad tracks and place a quarter on them. After the uptown 5-train or 2:10 to Brewster came and went, you'd have a flat, shiny disk. (And while turning money into mere metal was pointless, it was still more positive than frying ants with a magnifying glass.)
Pretty neat, a silver ring for 25 cents, right? Well, not exactly--turns out you need to use a quarter made in 1964 or earlier, when they still used silver. (The alloys in a more contemporary quarter will oxidize on your finger, leaving a sort of chemical tan line.) Coin dealers sell them for about $3, which is still a steal when we're talking jewelry prices.