VERY cool and impressive !!

Love it.

For younger animals one could still put a "tight" hide on each warm and cool side in the "burrow" And put a nice piece of driftwood and greenery on top, creating more privacy by adding stuff to "hide behind" or "sit on top".

Very neat indeed. You should sell your idea to a rack builder,lol, because I would love a rack like this in black, made out of PVC. I would like one long heat tape running throughout the entire rack. (I like this about mine). Basically going underneath each tub (in a recess), then up a side, underneath the next tub, up the opposite side, etc. Easy to control plus it adds a bit warmth to the upper portion of each tub, from the side the tape runs up on.

Very, very cool !!!