A musical instrument, such as a guitar, includes a transparent layer, an object formed in the transparent layer, a light source configured to transmit light into the transparent layer to illuminate the object, and a non-transparent layer over the transparent layer. The non-transparent layer is configured to inhibit the object from being seen through the non-transparent layer unless the light source is illuminated. A guitar may also include a neck and a body defining a sealed, hollow cavity that is fillable with a gas, a solid, a liquid, or a vacuum.