I have always wanted to give key copying a go like the secret agents do in spy movies, so I tried it using my house key. Before you freak out and say that key copying is illegal, note that I used my house key, which I own. Do not copy other people's keys. That is probably illegal and could be a felony.
Anyhow, I used some creative methods to quickly copy the key and cast it in zinc. After a bit of touching up, the casting actually worked! Check out the Instructable for pictures and more information! Also, if you don't believe me, watch this video of the test in my door: