I built my rat racks out of 1x2 furring strips... I used the arbreptiles.com design. Just had to change the dimensions slightly to compensate for the thinner pieces of wood. And I believe my tubs are a bit different.
With tubs and rats in them they're very sturdy.
1x2's I picked the straightest ones I could find, made my cuts strategically, and then when put together they all kinda pull each other straight.
~TruthsDeceit~
My house? ... 13 snakes, 3 geckos, a tarantula, a boyfriend, a roommate (yes the roommate and boyfriend make the "animals" list), 3 cats, a roach colony and don't ask me to count the rodents.
www.rodentworks.net Local to Bremerton, WA >Rats >Mice >ASF >Rabbits >Custom racks/cages