The synthesizer is a highly complex artefact. It is frequently employed in the music industry and renowned for its varied sound qualities. It employs rudimentary components such as buttons and knobs and is thus not equally renowned for its rich interactive possibilities. Through explorative research, the thesis identifies that interaction on synthesizers has stagnated and explores, through a lens of interaction design, how designers might utilize interactions such as gestures to control sound parameters for musical expression and how these interactions can affect this expression. Through design activities such as prototyping, this thesis reveals that gestures and hand movements feel natural and easy to grasp for musicians, and that it can change their way of playing.