There are several sizes of square seal ring material listed on Ebay right now, in dimensions from 3/16" to 1/2". I can think of all sorts of uses for that stuff. Search for "Square Buna-N O ring"
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!