A: An injection mold is a tool that is used to form parts in the plastic injection molding process. Tools are custom designed to allow for a specific part geometry, size, cooling methods, and injection pressure. Moulds can be built with a single cavity to build one part at a time, multi-cavity for several parts at a time, or family to build several different parts at the same time. Tools can be built out of several different metals including aluminium, steel, or hardened steel, depending on the life cycle required.