A constructional kit comprising elongated connectors and panels. The elongated connectors can only be joined to panels and the panels can only be joined to connectors. Elongated connectors have no means by which they can be joined to other elongated connectors, and panels have no means by which they...http://www.google.es/patents/US4334868?utm_source=gb-gplus-sharePatente US4334868 - Constructional kits
