This looks like a particularly entertaining design for a cage. It’s pretty cramped but, from a casual inspection, it would appear to rotate, pivot and be movable. The design is nifty, but it would be a hard thing to explain to a visiting relative. Traditional square cages can at least be attributed to holding a dog. It reminds me a little of this artwork, which is described as a parrot cage, so perhaps you could just say you had an enormous bird that escaped. Or maybe that you’re building a giant globe and haven’t got around to adding the continents just yet.
I found this on the Geek Domme tumblr. I’m afraid I don’t have an original attribution.