WHAT IS INJECTION MOLDING? Injection molding is a process used to shape material into a desired form. This process most often uses plastic, but can use other liquid materials, even molten metals. First, a moldmaker creates a mold of the desired shape from a metal. Then, the liquid material can be forced into that mold, where it cools and solidifies into the end product. This process is used in manufacturing to create an extraordinary variety of items.