Abstract: The present invention is directed to an educational toy device adapted to the building of three dimensional constructions, which constructions, as a principal sub-component, are based upon the configuration of an equilateral triangle. The device is characterized by a plurality of strut members of equal length and a plurality of linking members arranged to receive the ends of the strut members, the linking members being essentially spherical and formed of an elastomeric, yieldable, high friction material. The linking members include a plurality of radially extending sockets so constructed and arranged as to permit the end portions of struts to be supported therein while allowing the struts to be moved angularly relatively to each other.