"Designers sometimes don't do things that are immediately functional but they are functional to our understanding of issues."
--Paola Antonelli, from TED talks 2008
This link will direct you to the work of guitar architect, inlay dab hand, and personal friend-o-mine Stan Vandruff.
Inlay, in my opinion, is the first blush of what art critics today call "process art." The work of selecting and manipulating materials echo in a finished piece. The interaction of the bending of the artist's intentions to the constraints of the medium and the medium's conformity to a final design, though intentionally hidden, still linger in the edges and curves of wood, shell, and bone.
Back of a truly excellent work of inlay lies a deep understanding and creativity on the artist's part. Not only are there dozens of wood varieties (each with their own resonance, timber, and 'sustain'), but even more types of shell that vary in luster, color, texture, and value. Some shells even change appearance depending on the light or the direction from which you view the material.
The remarkable thing about Stan is his encyclopedic understanding of the materials and their acoustic value. Also, his workshop (you can find photos on his website) is pretty awesome! You can even commission a custom guitar of your own through the site (link above in the first line of this entry)!