Nice set of planes for someone to use. The two thing I would change would be the side and back panels. I would have them inside the cage instead of out side the cage. So have the top and bottom are sitting on the side and back panel instead. This will make the cage a lot stronger and less chance of it to bow or blow out the top panel. The screws are holding most of the weight the way you made it. All you will need to do is make the side 1-1/2 inches shorter in height and the cage will be the same size as the one you have made. You will still have to cut 1-1/2 inches off the back panel for height and length and don't cut the top or bottom sheets down the 1-1/2 inches.
You can kind of see what I mean in this picture.
I also like sealed plywood over melamine for wood cages.
take care
Tom
