Im not sure how you'd specifically do it with glass, but Erin'sanimals made a video on dividing the detolf in general. She uses wood in this video, but I'm sure the same concept would apply to glass or any other material you would like to use.
https://m.youtube.com/watch?v=Kh9qYq9Cf7g
In the video, she essentially cuts it to size, then fits it and glues it into the detolf. Then she adds sealent so her hams cannot smell each other
