This paper describes how a classical instrument, the clarinet, can be extended with modern technology to create a new and easy to use augmented instrument. The paper describes the design process, technical details and how a musician can use the instrument. The clarinet bell is extended with sensor technology in order to improve the ways the clarinet is traditionally played and improve the performing artist’s musical and performative expressions. New ways of performing music with a clarinet also opens up for novel ways of composing musical pieces. The design is iterated in two versions with improved hardware and form factor where everything is packaged into the clarinet bell. The clarinet uses electronics that wirelessly sends sensor data to a computer that processes a live audio feed via the software MAX 7 and plays it back via loudspeakers on the stage. The extended clarinet provides several ways of transforming audio and also adds several ways of making performances more visually interesting. It is shown that this way of using sensor technology in a traditional musical instrument adds new dimensions to the performance and allows creative persons to express themselves in new ways as well as giving the audience an improved experience.