[ebiggs1]

The easiest way to die cut any material is with a small press called a Clicker.
With this type die cut die you could cut thin copper, probably not heavy enough for exhaust material, however.
I found some gasket material at NAPA that is supposed to be good to 2000 degrees. It looks as if it will work well even on uneven surfaces because it is about an 1/8th inch thick and semi pliable. We'll see!