My dad built a treehouse with exactly this with liter water bottles in ~1994, he said he saw it when he was growing up with glass bottles. I hate to be a spoil sport, but this is hardly a new idea.
I've this guy on TV a long time ago. I'm certain it was at the 90's, but I don't remember the exact year.
It's not a new idea in any way, and was certainly invented more than once. Yet, it was this guy that (by luck) made the life of several people better by communicating it.
