Yes it is possible. I know someone who was given a glass-less model 211 and had a glass shop make a single door (lifts out in one piece). His was 1/4 inch glass, forgot if it was cheap plate or more expensive safety. The shop even beveled the edges slightly. He could have gone two doors, he just wanted a single because of the type of snake in that cage.
BTW, the person mentioned above experimented with a piece of 1/4 inch hardboard cut until it fit right. He took that hardboard to the glass shop for sizing.
Make sure you measure correctly and take into account the door track depth of the bottom track plus about 1/2 of the depth of the top track.
Im too lazy. I'd just pay the money and get the Vision glass, as it comes with a plastic runner on the top and bottom, is great quality and fits correctly.
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Mark