Abstract: A unit of child's furniture such as a chair or sofa is constructed of intersecting panels provided with a unique interlocking joint which provides strength, rigidity and long life to such furniture. In one form, each panel is made of a pair of triple wall corrugated cardboard sheets which are individually slotted and channeled to provide different portions of its joint, and which thereafter have their sides cemented together to form a double thickness corrugated panel. The furniture is preferably made so it can be transported and stored in flat, knockdown condition and assembled when needed.