I'm sorting out a vacuum chamber for my friend, we got a piece of 1/2" plexiglass cut into a circle 18" in diameter. I'll be hunting for a huge pot soon. But we need a seal of some kind. Any idea what or where we can get a gasket for the lid to pot? I read Viton is the material of choice for vacuum chambers? But I'm open to anything that works and doesn't cost a few fingers/toes.