I love skyscrapers! And those two are very attractive setups.
There are a lot of ways to create the unseen support for those types of vivs. The way I would do it is to just create a frame with eggcrate, zip ties, hot glue, something to cover it (like mosquito netting or weed barrier), and then the next steps kind of depend on what specific things you want to do. It will still be "3D" but it will also be way lighter than if you built it up with peat bricks or stones or perhaps even spray foam.
I did it with the skellig islands-style vivarium in these photographs:
(If you want to see the whole thread: https://www.dendroboard.com/forum/pa...out-sides.html
I noticed that, in your second photo, the builder of the viv wrapped hygrolon around a piece of wood / driftwood. (A little above the middle of the photograph.) It's possible that it's built of carefully stacked driftwood to provide a support, in the same way you'd build a bonfire. That's a little heavier than the eggcrate method, but there're no wasted materials if you decide to disassemble it, and the driftwood support parts can grow stuff on itself, too, whereas the eggcrate method can't.
Let me know if you need me to explain anything more clearly.