A modular and customizable construction for a guitar is disclosed. The construction may include a substantially flat metal guitar base plate that couples to interchangeable guitar components, such as a guitar body, a fretboard, and guitar string tuners. Further provided is a moveable nut that is used to adjust guitar string scale length via nut blocks that are separately adjustable relative to one another. Even further provided is a computer program product that allows for development of custom fingerboards that cater to a specific player's requirements and are optimized for alternative tunings and temperaments.