just shy of 1/8 inch. The characters are engraved in reverse on the back side of the plexi and filled in with paint. This provides a smooth front. When lit with a superbright l.e.d, the whole faceplate lights up.
I have access to a laser engraver. I make em out of plexiglass. An 11x14 sheet is $3. I can get about 7 covers out of 1 sheet. Any color or design u can think of.