Disclosed is a new method for making a component having interior and exterior threads. Such method includes the steps of providing a thread-forming apparatus having first and second circumferential threaded portions defining a space between them. Such space is filled with a flowable material, e.g., hot plastic, which is permitted to solidify and form the component. The apparatus and the component are then separated from one another by rotating such apparatus so that both threaded portions unscrew from the component. The finished component has interior and exterior threads which are simultaneously formed and substantially free of flashing. The new thread-forming apparatus has a first threaded portion and a pocket. A plug is in the pocket and has a second threaded portion spaced from the first threaded portion.