by using an existing ball nut and ball nut screw of a ball nut screw assembly as master models , imprint molds can be molded from a silicone rubber material which positively profiles the threading of the ball nut and ball nut screw with the crossover channel in the master model of the ball nut . a thermoset resin is added to the imprint molds and cured to form unitized all plastic ball nuts and ball nut screws with the helical grooving for accommodating the train of balls including the crossover channel in the ball nut molded therein to thereby provide an easily reproducable ball nut and screw assembly .