Abstract: A construction toy system comprised of a plurality of molded plastic girders and connectors. The girder elements of generally square cross section, with interlocking elements extending axially from each end. The interlocking elements each comprise a flange of square configuration, a groove structure of squared configuration adjacent the flange, and a generally cylindrical rod-like extension projecting between the end of the girder body and the groove structure. Connector elements are formed with one or more sockets for receiving interlocking elements of the girders. The sockets have one open side into which the interlocking elements can be inserted with a lateral snap-in action. The flange portions are freely received in a slot formed in the socket, and the groove structure engages and cooperates with opposed locking ribs formed on the sidewalls of the connector socket. Opposed axial grooves in the socket sidewalls engage opposite side portions of the rod-like extension with a snap-in locking action.

Abstract: A panel for a multi-part construction toy characterized by having recesses along some or all of its side edges for the locking reception of connector elements of the type incorporated into standard K'NEX multi-part construction sets. The panels are designed for snap-in assembly of the connectors, enabling panels to be joined edge-to-edge to form a substantially continuous wall structure. With right angle connectors, panels can be joined edge-to-edge at right angles. The panels are also provided with central half slots, enabling two panels to be joined with each other in an X-shaped configuration.