Humidity has been pretty easy with the coco coir. I just make sure to keep that moist. And lower down, we have the coir too. He also soaks a lot. I soak him and he hangs out in his water dish a few times a day and both drinks and soaks....which I understand is unusual for a Russian to do voluntarily. He's still a baby. This is our solution until he goes outside in summer, then we'll build him something bigger for next winter.
WOW! That's really nice! Be careful to watch him on hat ramp, it's pretty big! I'm jealous that he soaks himself, my russian is like a bad little kid!
That looks awesome, I love the idea!