A cavity plate assembly (400) for a preform mold (100), which includes a cavity plate (410) having an array of seats (412) and a corresponding array of cavity inserts (440) mounted to a front face (CVF) of the cavity plate (410) and in communication with a respective seat (412). Each cavity insert (440) includes a body (441) with a mounting face (441a) and a spigot (443) projecting from the mounting face (441a) and received in a respective seat (412) of the cavity plate (410) such that the mounting (441a) face abuts the front face (CVF) of the cavity plate (410). Each cavity insert (440) also includes a molding surface (448) along its length, at least two thirds of which extends beyond the cavity plate (410).