if it just cracked down the middle i would have a piece of 1/8" plexi or acrylic cut to size and just silicon it in on top of the piece. once it sets you shold not have any further problems
i already replaced a side piece approx 24 x 18, its a hassle. but not the end of the world, the glass...
i have a EXO TERRA terrarium, of which the right side glass door broke
it is a 36" x 18" by 24" hi
the glass for the door i can have cut locally, its a 5/32 in and i found a local glass place that has it
its the top and bottom rails i need, and has to be able to accept the thickness of 5/32...