We articulate vulnerability as an ethical stance in soma design processes and discuss the conditions of its emergence. We argue that purposeful vulnerability - an act of taking risk, exposing oneself, and resigning part of one's autonomy - is a necessary although often neglected part of design, and specifically soma design, which builds on felt experience and stimulates designers to engage with the non-habitual by challenging norms, habitual movements, and social interactions. With the help of ethnography, video analysis, and micro-phenomenological interviews, we document an early design exploration around drones, describing how vulnerability is accomplished in collaboration between members of the design team and the design materials. We (1) define vulnerability as an active ethical stance; (2) make vulnerability visible as a necessary but often neglected part of an exploratory design process; and (3) discuss the conditions of its emergence, demonstrating the importance of deliberating ethics within the design process.