You can't import new cans or get replacement parts from the Canadian mfg anymore, so I had to make do. I lost a lid gasket to one of my cans and the other had a rubber gasket. Rubber swells and could potentially break the retainer if I used the can for gasoline. Viton can be used for both gas and diesel.
* I used a 12"x12" 1/8" viton sheet stock.
* tacked sheet stock to a piece of plywood.
* used a 3 1/2 inch holes saw to mark center and edge. did not go all the way through.
* used a 2 inch hole saw to cut out the center - this is the most critical dimension as this is the edge that is retained.
* finished cutting the outside with 3 1/2 inch hole saw.
Its slightly larger outside diameter than stock so I had to hand trim the outside edge. I didn't have a 3 1/4 inch hole saw, but that probably is the right size, and wouldn't require any trimming.
No leaks
I'd take one or two