You can buy one custom made or make on for yourself out of PVC, plywood, or melamine. A 4' x 2' x 2' is a good size. Of course, if you can, go bigger. If you get one custom it will be much more expensive though. Here is a good thread: viewtopic.php?f=75&t=171697
Mirage came out of brumation on April 26. He was doing great. On May 2 he started acting funny. We just redid his tank, and he keeps going into one of his hides. He just lays there. He shows no intrest in food. HELP!