I picked up an American Friction Rock Bottom Glass last year and I LOVE it-
It's the sweetest sounding call I've ever owned- I'm not quite sure exactly what type of Wood the pot is made out of but it sounds Great and I wouldnt trade for squat!
I shopped for about a month looking at Glass and Slates from different makers and decided to go with this one, cant remember why I chose this paticular one but I'm glad I did
Good luck on your journey