Building toy

Claim 1

A BUILDING TOY COMPRISING A PLURALITY OF STRUCTURAL UNITS CHARACTERIZED BY AT LEAST TWO FEATURES WHICH MAKE MATING INTERFIT BETWEEN SAID UNITS AND CONSEQUENT ASSEMBLY THEREOF INTO AGGREGATES POSSIBLE, SAID FEATURES BEING SO DISTRIBUTED AS TO PERMIT SUCH UNIT INTERFIT AND AGGREGATIVE ASSEMBLY; (A) SAID STRUCTURAL UNITS BEING TUBES WHICH ARE SQUARE IN CROSS-SECTION; (B) AT LEAST ONE OF SAID FEATURES BEING NOTCH IN AT LEAST ONE OF SAID TUBES, SAID NOTCH BEING DEFINED BY END SURFACES OF WALLS OF SAID ONE TUBE, SAID END SURFACES LYING ENTIRELY IN TWO PLANES, SAID TWO PLANES INTERSECTING EACH OTHER AT A RIGHT ANGLE, THE LINE OF INTERSECTION OF SAID TWO PLANES BEING IN A FIRST AXIAL PLANE CONTAINING TWO DIAMETRAL CORNERS OF SAID ONE TUBE AND BEING PERPENDICULAR TO A SECOND AXIAL PLANE CONTAINING THE OTHER TWO DIAMETRAL CORNERS OF SAID ONE TUBE, SAID FIRST AXIAL PLANE BISECTING SAID RIGHT ANGLE, WHEREBY TWO MALE TUBE SEGMENTS SYMMETRICAL ABOUT SAID FIRST AXIAL PLANE ARE FORMED; IN THE FORM OF A FEMALE NOTCH IN AT LEAST ONE OTHER OF SAID TUBES FOR MATING WITH AT LEAST ONE OF SAID TWO MALE TUBE SEGMENTS, EACH SUCH FEMALE NOTCH BEING SO POSITIONALLY ORIENTED ON ITS RESPECTIVE STRUCTURAL UNIT AS TO PERMIT MATING ENGAGEMENT OF ITS UNIT WITH, AND IN AXIALLY PERPENDICULAR RELATIONSHIP TO, ANOTHER OF SAID STRUCTURAL UNITS HAVING A NOTCH AS DEFINED IN SUB-PARAGRAPH (B).