That is very nice! Initially I thought that was a picture background, but the close up pics shows that the rocks are real stuff that they can climb on, awesome!
How big a set up is that? I have thought of attempting something on that order. Not with the frails of heated rocks though. I used to make real rock backgrounds for inside fish tanks. Curious about cleaning something like yours. Looks like from the photo it might have a clear coat or other finish on it. Its the coolest I've seen. Really, really, nice.
Take care. / HJ