Re: My ratlets' cage
Some rat owners have used velcro with success, though they all admit that it gets a bit icky after a while

But, I'm sure velcro isn't that expensive and can be replaced fairly often.
Towels control odor extremely well! In fact, if you're switching from Carefresh to towels, you should notice a huge difference. Personally, I can't stand the smell of Carefresh, especially if it's a little dirty. For the litter boxes I have in my cage, I use pelleted litter (such as Yesterday's News), since other litters are too light and will just be kicked out.
Towels can be a teensy bit of a hazard, though, since if they're chewed, they become stringy and rats can get their feet/nails caught in them. I've used towels for about 7 years now and have never had that problem. Just cut off any loose ends before you put the towels in the cage

Fleece, on the other hand, doesn't have that problem. Fleece is also fairly inexpensive, too, and comes in a wide array of colors and prints. I use a mixture of both in my cage.