I assume you are talking about the cylindrical gasket that goes, say in the crossover pipe or in the exhaust pipe where the muffler slides in. Some of these cost, I think, $30 or even $60 (priced them last year, don't remember actual price except it was exorbitant). I just reused mine since it was not damaged after I removed the muffler and exhaust manifold/header pipe. The header 'gaskets' are hollow copper O-rings that crush when you tighten the nuts and are cheap ($3 to $4 each).
To answer your question - no, I did not try to make my own.
