Believe it or not, it CAN be done right here in the desert! LOL

I've got a 15gal set up with a screen top. I covered about 85% of the top with clear contact paper. (Covered the whole thing, then cut each of the four corners out so air will circulate nicely.)

The substrate inside is that coconut stuff that you buy by the brick and soak in a bucket of water. When that is dry, the humidity levels can drop to 20%. I have a bucket of moist, fresh substrate tucked away nearby. I put two handfuls of fresh, moist stuff in the cage and swish it around. The humidity rose quickly to 65%...and will go higher if I put another handful in. It took several days for everything to dry out again with the humidity very slowly dropping back down into the 50's. When it reached 45, I took a couple handfuls of the dry stuff out and replaced it with a couple handfuls of moist....and boom...instant, constant humidity! (Well, constant for a few days anyhow....beats misting 2-3 times a day!)

Just thought I'd share....