You can get the glass cut at auto glass installers. you want the thinner safty glass (lamanated), I would stay away from the tempered glass like side windows, the ball shock might shadder it.

Have them grind all the edges for a 45 degree flat 1/16 to 3/32 inch all sides and front and back. That way it will seat in the glass troufes. Weasure tight fit and than back off a 1/16 inch.

Thought I would pass a little info on.

Note get Clear not tint.

UPDATE yes you can use tempered glass, the newer process gives it stronger tensel strenght, remember to have them bevell all sides so it fits in the grove well