Injection molding can be used for a bridge tooling, trial run and low- to mid-volume production before volume production. CNC machining is suitable for making prototypes and mid/low volume production. Urethane Casting is usually for creating prototypes for product development. Do you know any other differences among these three processes? Please check this video, maybe it could give you some tips. Please visit: www.dankemold.com to get more information