In this paper we explore the idea of transforming a portable speaker into an interactive music sketch pad using low and high fidelity prototyping. We present research into the cur- rent state of the art of musical sketch pads and specify the requirements for a new concept based on pressure-sensitive conductive fabric. We developed a virtual prototype and subjected it to user testing. Results from the user test led to the design and implementation of a high fidelity proto- type based on a single-board computer with an additional audio interface communicating with a custom embedded MIDI controller. A real-time, loop-based musical software platform was developed as part of the high fidelity proto- type. Finally, user test results are presented and discussed.