[Stefan-A]

So I've used them for less than a year now, and I'm generally happy, after a number of modificiations to the ventilation and doors. Now here comes the next insane plan:

Does anybody have any ideas on how one of these could be turned into something that can stand a lot of humidity? Wood and water (vapour) coming in contact with each other doesn't seem like a good idea. Is there anything that I could cover the inside with, for example?