Re the top entrance box last shown- my co-worker tried it (multi-cats) and it failed. (Cats peed on the top of it).
She swears by the expensive http://www.pfprivy.com
I am going to spend the 160.00 to try it. It's just a well made cupboard with tracking that forces the cat to walk across it. I have a tiny apt. I walk and sleep on litter! Anything to limit this is a miracle! I have tried the plastic runners from the hardware stores and pet stores and they work, but scamp pees on them. He won't have the room to squat and pee on this one. My co-worker bought one at a cat show (friskies) 2 years ago and really liked the woman who makes them. Anyway, they are advertised in cat fancy magazine. Does anyone else know anything about them before I make the plunge?