I have 2 cube/coroplast cages that I am thinking of remodeling to save space. What I want to do is put one on top of my 4x2, which already has an opening top to it. My only concern is, the 4x2 is split in half, so i wont be able to get to one cavy! Is there any way to make a opening door on the side of the cage? Any help will be greatly appreciated.