I have had really great experiences with my chins being in 'cat cages'...lemme find a link...
Here ya go. What happened was, I got Rodya and Sonya with the cage they were being kept in when bred by previous owner...I hated it. I thought it was way too small, and she could only afford to the take the time to clean the cages thoroughly once per YEAR, so it was really ****ty, in the chin poo sense. So I was browsing on CL because Petco cages are terrible, and I didn't know about FN cages at the time, and I found an ad for a 'cat' cage. Like in the picture, it has a solid bottom and wheels for mobility, and it came with 3 shelves--one long, 2 short, so that the ledges/shelves vary. The 2 short ones were covered in carpet, but I stripped that, and then set it up for Rodya and Sonya. It works great, except that it isn't baby-safe, and when Ivan was too small for it, he had to be put in his parent's original cage.
When I got Mork and Orson, I knew I wanted another cage just like Sonya and Rodya's, so I put an ad out and found another cat cage, this one with a really really nice bottom--the guy I bought it from was a woodworker, and he made a custom bottom with leftover kitchen tile for easy clean up--I love him for that. SO much easier than cleaning my first cage, and there is a 1/2 inch wooden lip to hold the cage in, rather than a little trenchy-type thing dug into the flat surface, like in the first cage--not as much poo & litter gets thrown out of Mork's cage. That cage came with 2 nice wooden shelves, too.
The first cage cost me $60 and the second cost me $80, both are collapsible only with 2 people and without the bottom attached to it, no shelves, etc, so there's no way they could have a collapsing accident with my babies inside. They're really large when standing upright, too, and then I have some space to put their toys and treats and things on top of the cage. They both have 2 doors, one on the top half and one on the bottom, although the size and placement of the doors is different for each cage.
I've never had a cat so I didn't know there were such things as cat cages, aside from the carriers you bring them to the vet in, but I have actually seen them, now that I know what to look for, at Petco and Petsmart--for about as much as a FN. Both guys I bought them from told me they'd had to buy them for a certain cat which was abusing the other cats in the house while they were at work. So they'd put Fluffy in the cage during work and let him out at night when they were home and able to keep an eye on him. Probably why the cages were so large, so kitty could jump and play and scratch, etc.
Just a random thought when reading this page