Maybe this is the plan that Nick was referring to that I posted a few months back.
If so, feel free to copy it to your hard drive for a reference.
I used plain untreated pine for the one that I built, and have had no problems with
mold or fungus, but treated or sealed pine or cedar (more expensive) would be
much better, especially if you are going to keep humidity levels in the very high range.
Mine averages 55% low to 85% high.
As soon as I finish the r/c model airplane that I am building for my dad, I am going
to replace the flat top with and inverted V-shaped one because I think the air will
circulate better and more of the heat from the internally mounted lights will escape. Mine goes into the low 90s during the summer which doesn't seem to hurt anything, but I prefer to keep it at 85 to 88 degrees maximum.
Hope this helps.
Alan