In this paper, we present a case study of the iterative design of TalkingBox, a communication device designed with a person with a severe cognitive disability and his support network. TalkingBox combines graphic symbols with tangible technology to foster the use of symbolic communication by leveraging the person's strength and interest in memory matching games. In the course of designing, trialing and iterating the TalkingBox, we discovered that the design supported not only the development of symbolic communication, but also revealed new interests and strengths of our participant. TalkingBox highlighted opportunities for interactions with peers, revealed new skills in visual discrimination, and evidenced interests. These could, in turn, support staff and family to adapt their support. More importantly, TalkingBox had become a living portfolio presenting our participant with severe disability through the lens of their strengths. We discuss opportunities for research through co-design to open new avenues for future communication technologies.