This book provides a comprehensive overview of the knowledge of musical instrument physics and its practical application in musical instrument making. It focuses on two key aspects. Firstly, the basics of the physics of musical instruments are the role and properties of each component and how they all work together. The essential characteristics of instruments are studied through concepts such as harmonicity or auto-oscillations. The role of materials, including composite/synthetic materials, is also discussed. Secondly, the tools developed by physicists and engineers over the past century to enhance instrument design and manufacturing will be reviewed. Topics covered include numerical aspects of instrument virtual synthesis, modeling interactions between interconnected subsystems, solving auto-oscillation processes, optimizing instruments, and essential experimental techniques for instrumental characterization (mechanical and acoustical). Throughout the book, applications to real instruments are underlined.