"The bird is about 55% tin, 25% zinc, 2% copper, and the remaining 18% bismuth. I was going for a 'golden bird' type of appearance without having to do any further modifications after the initial cast, which I was pretty happy with. Tin/copper doesn't get along too well with bismuth by itself, so I put in a bit of zinc. I oxidized the molten mix for a bit on low flame, so I had some bismuth trioxide already, heated the mold so it would cool more slowly and have more time to oxidize the surface, and poured it in. Voila! I spend way too much time testing this stuff out in my garage, or so my teachers would have it."