The design of a digital musical instrument is often informed by the needs of the first performance or composition. Following the initial performances, the designer frequently confronts the question of how to build a larger community of performers and composers around the instrument. Later musicians are likely to approach the instrument on different terms than those involved in the design process, so design decisions that promote a successful first performance will not necessarily translate to broader uptake. This article addresses the process of bringing an existing instrument to a wider musical community, including how musician feedback can be used to refine the instrument's design without compromising its identity. As a case study, the article presents the magnetic resonator piano, an electronically augmented acoustic grand piano that uses electromagnets to induce vibrations in the strings. After initial compositions and performances using the instrument, feedback from composers and performers guided refinements to the design, laying the groundwork for a collaborative project in which six composers wrote pieces for the instrument. The pieces exhibited a striking diversity of style and technique, including instrumental techniques never considered by the designer. The project, which culminated in two concert performances, demonstrates how a new instrument can acquire a community of musicians beyond those initially involved.