I looked through the whole gallery of user-build C&C cages but did not see any three level designs. I have a rather large area that I will could build my cage in, but I'd prefer to use a 3 feet x 2 feet area next to my book case, and I can make it three level. This will give two guinea pigs 18 square feet of room. It will need to be closed as I have plenty of rascally cats, but before I commit to the design, I need to be sure it can be done. I want to make sure I'm giving the guinea pigs as much space as possible before bringing any home. Do any of you have a three level C&C cage? If so, do you have any advice, and can you share pictures? If it cannot be done, would you mind explaining why?