I think you're referring to a shrinking disc. I've got an issue of Car Kulture Deluxe with an article about this method.
I've never heard of anyone making one out of a frying pan.
Sounds like danger......... but now you've got me wanting to try it!
I think guys usually make them out of stainless.
http://www.youtube.com/watch?v=qYXMY07m8Is