Chewbacca’s design stemmed from a George R.R. Martin story. The Chewie that Star Wars fans know and love is actually based on a John Schoenherr sketch for George R.R. Martin’s novelette And Seven Times Never Kill a Man that appeared in a 1975 issue of Analog Magazine. The story goes that Lucas showed artist Ralph McQuarrie the sketch, telling him that he believed it was from the 1930s, and wanted McQuarrie to use it as the basis for Chewbacca. McQuarrie added Chewbacca’s bandoleer and the wookiee was given more of a protruding jaw and taller forehead in development.
This is called Aluminium oxynitride; aluminium compressed to it's theoretical max density and becomes transparent. Also known as AlON and is used for bulletproof glass. 
