Be careful what you buy from Lowe's and Home Depot. Sometimes they sell a low grade melamine with a paper coating rather than a plastic coating. You can find melamine pre-cut into 24x48 boards with the plastic coating for around $10-11 each. This is a pretty good size to work with. Get 2 sheets and have them cut 20" off the length for your sides.
Screw your top and bottom with your sides to the inside of the cage structure.....so your side walls are sitting on your floor and your top is sitting on your side walls. ALWAYS PRE-DRILL YOUR HOLES WHEN USING MELAMINE.
If they have plastic coated melamine shelving, get one piece and have it cut into 2-3" strips for use as a litter guard on the bottom and top of the cage face. When attaching these, place them 1/8-1/4" inside the front of the cage.
Get a sheet of white shower board (dry erase) for the back. A 4x8 sheet is around $10. This can be cut to fit the back of the cage and can also be cut for vent placement. Before securing the back, caulk the inside front of the cage where the litter guard is. Trust me, it's so much easier to do it before the back it on.
As for the sliding glass, you can find the tracking at
www.outwaterplastics.com. It should tell you how to measure glass for your opening.
Here are some chondro cages I built last year. These are all 40 x 20 x 20 and 30 x 20 x 20. Because of the black melamine, they ran me about $80-90 ea completed. The smaller cubes on top are 20" PVC cages.
