I wouldnt use cedar because Wood from western red cedar has one of the most potent insecticidal compounds, which accounts for its popularity to repel or kill clothes' moths. These same chemicals can also damage the respiratory tract, causing chronic respiratory disease, and asthma .I cant imagine living on it could be good .
Im not sure about treated lumber .. I do know I used regular pine lumber which I put several coats of poly on, for my iguana ,I mist the cage heavilly twice a day and keep two cat litter trays of water in the bottom level (its tri level) and have yet to have water damage.
Ive recently made cages for cresteds that have worked out very well so far . I purchased craft grade lumber from chase pickens (pre-cut at 18 x2x 1/4 and 1x1x36 made a box kite style frame , stapled 36 inch fine mesh window screen and decorated to suit me with silk plants and driftwood . The entire cage weighs maybe 15 pounds and can be washed out with a water hose .Cost about 35 bucks ,dont get musty and even seem to be cricket proof. They do require regular misting however.