This device is a precision-crafted tool for making router cuts on the neck and body at the heel which will be used to attach the neck to the body.  This tool is carefully calibrated  to create precisely the right amount of forward tilt in the neck when it is attached to the body in order to provide an optimal string action in the completed guitar.  Tools following this concept have been used for many decades in steel-string guitar construction.

The clear plexiglass plate on the right side of the tool is a template for guiding the router.  The  template in this photo is for creating the male part of the dovetail (called the tenon) on the neck heel.  Another template, the opposite of the one in this photo, will create the female part of the dovetail (called the mortise) in the guitar body at the heel.

The traditional classical guitar alternative to to my dovetail mortise-and-tenon neck attachment is known as the integrated neck.  Instead of installing the neck onto a completely assembled body,  the sides are first attached to the neck heel by inserting the ends of the sides into slots in the neck heel and gluing them in place.  The soundboard is then installed onto this neck/sides array using little individual blocks of wood to glue the soundboard onto the sides, a tedious and cumbersome process to say the least.  Then the back is installed with glue and clamps.

The problems with the traditional technique are numerous: it is difficult to control the body shape because the technique does not allow for the use of a mold; the tilt of the neck is unpredictable, making it hard to produce a consistent string action; the overall final structure is much weaker; installing bandings and purflings, the protective/decorative strips around the edges, is impeded by the presence of the neck  which gets in the way of cutting the channels needed for these components.