Mobile robots must behave intelligibly to be acceptable in public spaces. Designing social navigation algorithms for delivery robots requires different areas of expertise. The paper reports on an interdisciplinary collaboration between two ethnomethodological conversation analysts, a human factors psychologist, and two motion planning engineers. Based on video recordings of a robot moving among people, the team developed and implemented different sound and movement designs, which were iteratively tested in real-world deployments. This work contributes insights on how interdisciplinary collaboration can be facilitated in the area of social robot navigation and an iterative process for designing robot sound and movement grounded in real-world observations.