Thanks fellows!

Duck, I get the mica off of ebay. Had this stuff for several years from a guy who makes his own. Priced about the same everywhere I've seen it ($$). 
The shades are based on the Woodcraft? dimensions and one can get two shades from a single sheet. Not sure if the guy is still making it, last time He asked of I wanted free "scraps" and extra sheets and I got a whole bunch of large pieces.