Abstract: This fastening device comprises a central internal plug formed with retaining notches and engageable in an external peg consisting of separate legs formed with internal and external notches and connected to the inner end of said plug by means of flexible strips molded integrally with said legs and said plug. The legs are folded against the plug and the latter comprises a flange for limiting its inward movement and means for supporting the object to be fastened. The assembly is molded as a one-piece member in a three-section mold with one joint plane formed with the impression for molding said legs in a plane perpendicular to the axis of said plug, said plug being molded in the other mold sections.