Polyhedral elements with undercut recesses and cylindrical connectors having collars

Claim 1

Construction toy, comprising (a) a polyhedral base element having at least one plane face and a recess opening onto the face, the surface of the recess being in the form of the frustrum of a cone with the larger diameter located inwardly of the face, the depth of the recess being substantially less than said diameter, and a bore leaving the center of the bottom of the recess and extending through the base element, the said surface of the recess extending completely from the said face to the said bottom, and (b) a connecting member consisting of a short cylindrical portion having a diameter less than the smallest diameter of the recess in the base element and an integral circumferential collar in the form of an annular surface, and a bore extending axially through the member, the diameter of the collar being greater than the lesser diameter of the recess said annular surface having means including rounded edges longitudinally of said cylindrical portion to co-act with said recess surface and aid movement of said collar into said recess, and (c) a second polyhedral base element with which the connecting member is connected, the cylindrical portion extending from a plane face thereof, the distance from the latter plane face to the outer end of the connecting member being less than the depth of the recess.