We describe a co-design method for development of an assessment tool for chronic pain. Here, by taking a "research through design" approach, we visualized and shared various strands of our domain knowledge. From this, a common understanding of the relevant issues was seen to emerge, which in turn facilitated creativity among the group. Thereafter, a collective proposal for a pain assessment tool was formulated After outlining this proposal, we move on to argue that, based on our experience this method provides a useful platform for interdisciplinary collaboration in healthcare technology development.