Terhorst Manufacturing is a Manufacturer of Injection ... Plastic injection molding, insert molding, plastic injection mold designing, custom injection molding, plastic tooling, Terhorst Manufacturing, Minot, ND, cnc milling, agitators, roller ends, tank fittings, Terhorst Manufacturing is a Manufacturer of Injection Molds and Custom Tools and Dies. Our state-of-the-art equipment allows us to turn custom designs into finely machined, accurate molds for injection process and wire or metal insertion.