Body as Instrument explores how musicians interact with movement-controlled performance systems, producing sounds imbued with their individual physical signature. Using motion tracking technology, performers can translate physical actions into sonic processes, creating or adapting novel gestural systems that transcend the structures and constraints of conventional musical instruments. Interviews with influential artists in the field, Laetitia Sonami, Atau Tanaka, Pamela Z, Julie Wilson-Bokowiec, Lauren Sarah Hayes, Mark Coniglio, Garth Paine and The Bent Leather Band expose the transformational impact of motion sensors on musicians' body awareness and abilities. Coupled with reflection on author-composed works, the book analyses how the body as instrument metaphor informs relationships between performers, their bodies and self-designed instruments. It also examines the role of experiential design strategies in developing robust and nuanced gestural systems that mirror a performer's movement habits, preferences and skills, inspiring new physical forms of musical communication and diverse musical repertoire.