Rapid tooling allows you to use the actual production grades of material, allowing you a much clearer picture of how the parts will act in real-world applications and enabling you to test and confirm you have made the correct material choices. Parts are also injection molded as they would be in production so you can also use them for stress and impact testing, for example, exploring any weak areas due to weld lines or other imperfections from the injection molding process such as shrink and warping. With this information, you can then better determine if any changes need to be made before expensive production tooling.
People also use rapid tooling to test the parameters of production and ensure they will get parts that fill correctly and act as desired. In this way, engineers and designers are able to catch a lot of future process flaws and implement redesigns or other measures to prevent issues with the final parts.
