What to set the cage on?

Right now I have Thelma in a 20 gallong aquarium. I just don't trust the top. I am thinking of getting a plastic container for her. What do you guys sit your containers on? I know that her new cage will be longer and wider than her aquarium. Right now I have it on a bench with wood on top of the bench. Also, can you recommend a good top for the 20 gallon? I am thinking about moving my corn snake into it, as she is really getting big. Also, can I safely use the UTH with the sterlite or rubbermaid containers? I know these questions have been asked and answered a million times. So I guess this will be the millionth and one.

Yes you can put a UTH on a rubbermaid/similiar container. Just make sure it's regulated by a thermostat, but you should have one of those anyway. ;)

I use a rack, but when I had a tank I had a nice little stand with storage underneath. I know others use bookshelves, dressers, floor. The only thing would be to elevate the tub a half in or so off the ground for good air circulation. I used little blocks of wood for my tank, but whatever works. :D