If you placed an order for the manufacturing metal mold then later realize that your design has flaws, it will be very costly to rework the mold. Reworking a faulty mold is sometimes almost as expensive as the mold itself. Making a test mold is only 30-40% of the cost of a mass production metal mold. By purchasing a test mold prior to manufacturing, you guarantee that your parts are fully functional before making the manufacturing metal mold. Further, it saves you the incredible potential losses you could incur if your order for mass production results in a flawed product.