ply wood works, i just built one and got a 8x4 ply for $6, made a 4x3foot table, it took like an hour to build, and will be housing my torts. through the winter...
Mine is also made out of plywood. It only took a couple hours to build, but I had to wait overnight for the wood sealer to dry. I built the table, then sealed it with Thompson's Water Seal. I used 3/4" plywood.