Kami No Tsubo/Hiroshi Kajimoto

I found these makeshift vases that you can make yourself; the design, Hiroshi sells the kits which you assemble yourself around a plastic bottle. I like the concept of how he's taken a plastic bottle, something you'd either throw away or recycle, into a more useful piece.

http://en.kamigu.jp/item/kaminotsubo.html