Abstract: A mold for forming a plastic article having an undercut or negative draft portion adjacent a narrow wall spacing, such as a card rack, wherein the hollow projection extends outwardly from an article wall which is substantially normal to a rear wall of the article so that the projection and the rear wall are in facing relation. The mold is particularly adapted for vacuum forming an article and includes a mold member that may be heated and cooled to form and release a plastic article and a frame for holding peripheral edges of a plastic sheet in overlying relation with the mold and a heater for heating the plastic sheet for vacuum forming to the shape of the mold.