GuitarBot a robotic musician designed to play an acoustic guitar in a rich and expressive manner. The robot can play with a wide dynamic range, millisecond-level note generation, and a variety of playing techniques such as strumming, picking, overtones, and hammer-ons. To allow for these capabilities, human guitarists were recorded and studied, leading to the development of models that were implemented in both hardware and software design.  A number of iteration have been developed for the GuitarBot using a variety of actuators and collaborative HRI schemes.