Abstract: An attachment block structure for connection through a preformed opening in a first workpiece to provide a fastener receiving surface to permit attachment of a second workpiece to the first workpiece comprises a first plastic member having a plurality of resilient legs depending from a radially extending flange. Latch elements are carried by the legs for retaining the first member in the preformed opening. The flange has a central passageway and a radial extent greater than the preformed opening to define a limit for movement of the first member into the preformed opening. A second plastic member is associated with the first member and has a body with an exterior surface sized to be closely received in the passageway of the first member to prevent radially inward deflection of the legs when the second member is inserted in the passageway.