Copper is the best, but I also scrap aluminum, stainless steel, and brass. The most recent scrap was four window a/c units. To maximize the nonferrous (non-magnetic) metals I break them open and cut out the good stuff. I also scrap the ferrous stuff (magnetic metals), but you don't get very much for it. It's more of a hobby rather than something to live off of, but it does allow me to buy some silver.