PSB uses aluminum fronts and backs on some of their speakers. I believe I've seen some others use complete aluminum cabinets as well, probably more of a "lifestyle" setup like a condo HT or similar.
I have never understood using glass enclosures. Glass sounds like a bad idea all around. They might look nice in a "lifestyle" setup though.
I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.