This thesis outlines the design and development process of an assistive musical technology: Bean, which was designed for use in a music therapy setting. This instrument is tangible in nature. An initial ergonomic design, guided by the principals of Inclusive Design, was created. Interaction with Bean is tangible with enactive traits. A modular structure, facilitated by rapid prototyping techniques such as laser cutting and microprocessor technologies such as Arduino, helped provide a flexible prototype for usability testing. A participatory, user centered evaluation of the prototype was carried out to primarily assess if Bean was simple and intuitive to use, and if it was relevant for use as a tool in a music therapy setting. Other aspects of the design were also assessed. A certified music therapist, several groups of clients with a variety of complex needs, family and staff members participated in the evaluation. Three test sessions were carried out over two days, with a total of 22 participants (13, 7 and 2 clients respectively). This evaluation resulted in the suggestion that Bean is in fact a relevant addition to the music therapist’s tool kit. The majority of participants found Bean simple and intuitive to use, though with the caveat that Bean lacked some flexibility in use for those with complex physical needs. There was also a consensus that Bean was fun, and enjoyable in use.