This was on BabyGadget a little while ago, the FYS Finish Your Self Junior chair made of recycled cardboard--oh wait, no, it's "100% recyclable"--by David Graas, an Amsterdam designer interested in environmentally sound products, or as he puts it "designing better garbage." [I'm not sure if he's yet surpassed the brilliance of his first project, the Supersize Lamp, made from two McDonald's cups. You can download instructions on his site. 2013 update: or not. Look here for Graas's Supersize Lamp.]
Anyway, recycling also works for design ideas, and Graas' slot-together structure probably has as much to do with the characteristics of the corrugated cardboard itself as with Papanek & Hennessey's disposable car seat idea published in their classic handbook, Nomadic Furniture. Great minds, etc. etc.
Finish Your Self Junior chair, and a bunch of other designs by David Graas [davidgraas.com via BabyGadget]
Previously: Nomadic Furniture on DT