Ok I have an alternative C&C using a thick foamboard with wire shelving. The shelving seems kindof wobbly. I'd like to add another level. (maybe even another cage) on the top of the first level. I'm not sure how to do this, what I should use. The foamboard won't work (I don't think) because of sag, and I don't have access to coroplast. If I used plywood (covered of course)m I'm afraid it would be too heavy? Linoleum would sag too much in the middle too much also right? ERG! What can I use? Any suggestions?