A jig apparatus for aiding in the formation of a variety of mechanically interconnecting structures in workpieces. The jig apparatus may include a base and a template mounting system for adjustably positioning a template with respect to the base. A securing system for securing a work piece in a desired position may be included. An adjustable workpiece mounting fence may also be included for varying the angular orientation of a workpiece to be shaped with respect to a template. Additionally, a collar guide system for a router for utilization with a template may be implemented with a hand held router being implemented for removing material from a workpiece. A router bit positioning system for aiding in establishing a pre-determined bit depth may be included.