Quote Originally Posted by paul_c5x4 View Post
My first choice would be someone like Edmund Optics, but they wouldn't be cheap by a long shot.. A low cost alternative would be a flat sheet of glass from an old Kodak safelight, but... Old glass is notoriously difficult to cut as it gets brittle with age and it may not be "heat resistant" enough.
Nice ideas! The Kodak safelight option is plausible though that glass is really thick...and fails one of my criteria (1mm thick)

Edmund, yep Neal has some info above...it works but then cost gets a bit much...

This is one of those riddles where you know something shouldn't cost that much to MacGyver but I seem so stumped finding the right material....

Keep the ideas coming...much appreciated