Mike, I'm looking to do that too. I'm on vacation till the first, so I won't be able to do it, but if you get anywhere please let me know! I found this bit of information online, not sure if it's accurate, but here goes:
"Best trick is to melt the Bismuth on an electric pot heater. Allow it to cool very slowly using a thermometer to make sure it stays *just* above the melting point. Using a pair of tongs, touch a small piece of Bismuth to the surface and hold it there while dropping the temperature to *just* below the melting point. Then lift the metal bit out after a minute or two. If you do it right, you can get some fantastic looking shapes."