Injection molding organizations determine their charges based on an hourly rate for equipment plus the cost of raw plastic per unit. The type of plastic used must be specified since not all plastics can be molded using the same metals in the molds. Injection molding is a good method for mass producing uniform plastic parts at a low per-unit cost, but the initial costs of molds, setup, and tooling are substantial. Some advantages of injection molding include high production volumes, tight tolerances, versatility in materials used, and low labor costs. Product designers should consider factors like shrinkage, draft angles, stresses, resin additives, and more when designing parts for injection molding. Custom plastic molds used in