How to Make Cardboard Furniture
From Howtopedia - english
Corrugated Cardboard is a cheap, light and rather resistant material. It is quite appropriate to make small furniture pieces as long as they have a clever structure design and are kept perfectly dry, and far from a heat source.
Links to Cardboard furniture designs
http://foldschool.com/: free patterns for a stool, a chair, and a rocker for kids [www.designboom.com/cardboard3.html www.designboom.com]
Or if you haven't the time or resources to construct your own then why not buy cardboard toys & playhouses at http://www.cardboardtoys.com - They offer huge discounts for schools & playgroups.