A hand-held instrument, with a rotary power input to a camshaft, has cam and follower arrangement to provide a reciprocating shaft output. Moreover, the channel thus defined has a sample-receiving chamber therein, a first port, and a second port. As a rotary shaft of an idler pulley is released from the tension arm through the cutout portion, the timing belt can be removed easily. The user may quickly begin creating desirable music in accordance with one or a variety of musical styles, with the user modifying the auto-composed musical composition, either for a real time performance andor for storing and subsequent playback.