Abstract: A custom-made tool used to control the location and/or movement of parts to be worked to complete an unfinished metal structure into a completed firearm receiver. The tool is a two-part jig fashioned especially for building a handgun receiver from a pre-shaped metal works without the need for other industrial tools or apparatus. Using only commonly available tools in most home work shops, the disclosed jig facilitates producing a firearm receiver from an unfinished metal structure. This disclosure also teaches a method for creating a completed pistol receiver from an unfinished metal structure using the invention.