I keep my mice in 10 gallon aquariums (bought used at yard sales) covered with ¼ inch mesh hardware cloth. I weight the tops down with 2 to 4 jars of water or else some large rocks, supported by large cake cooling racks.

I recently saw some interesting instructions for a snake rack, that might be modifiable for rodents, on the Cage & Habitat Design forum.
the interesting rack set-up