I thought about that but thought against it because I would always have one growing down. However, one more on top, like an axle, is in my mind. Get one in the middle growing straight up. I might cut a cup down just enough for the base so it won't be so top heavy. Savvy?
I could hang it but it would require making more holes in the cup, I wouldn't be able to do the top cup, and the center of gravity is not in the center. And inhaling all that burning plastic and all those caulking fumes can't be good for me. The caulking fumes are pleasant but the plastic is blech.