The above structure is allegedly a greenhouse surrounded by a safety perimeter to keep the children away from said greenhouse. Redditor Syyraxus's post is called "So my brother in law built this... thing, I had no idea what it was until my sister told the children to keep away from the greenhouse as it wasn't safe. Greenhouse..."
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.