I figured plastic was superior because it does have an insulation factor and is larger.

The tubs would be the enclosure. I would take cue from pro exotics as they use the same setup for their ackies(meanign they use troughs, although they do use metal). The plastic would allow 11+ sq ft of floor space where the metal allows under 8.

For the top I planned to make an attached "L" shaped top of Plexi 1/4" thick. Ceramic fixture on inside of top to keep heat under lid. The lid would allow direct access to a 1/3 of the tank. I hoped to make a dolly which I could somewhat frame to keep the tub from warping. Our dollies at work hold 3500 lbs. so weight should not be an issue.