I just built a wooden cage myself (2ft D x 16in H x 8ft length, it has four sections for four snakes, anywho...) and I lined the interior with corrugated plastic (plastic cardboard). It's made our of polypropylene which is the same basic plastic many reptile cages are made out of. Super easy to clean and disinfect the inside of each enclosure.

I used indoor/outdoor carpet glue to stick it to the wood. And used silicone to water proof all the corners. Looks real nice and is holding up really good. And it is slightly insulated since it has the air space inside of it so it helps with heat and humidity. You'll have to wait at least a week for the smells of the glue and silicone to go away though, that's the only bad thing. The plus side is building an awesome cage that houses 4 adult BP's for about 230 bucks.

I would think the wood inside the cage would kind of suck the humidity away if it wasn't covered with something.