I'm really into metal casting. Got into a few years ago by bastardizing a kiln I found on craigslist. Have since moved on to building my own propane furnaces and rigging old microwaves to melt copper. I don't know that I'm actually any "good" at it, but I do enjoy it a lot. I like working with a material that you have to respect highly or it will burn a hole straight through you. And I have been able to cast some rudimentary parts(housings, pulllies) that have been used on other hackeresque projects.