Assistive technologies (ATs) must improve activities but also the participation of impaired users. Thus when designing ATs, especially for children, one should consider the diversity of users and disabilities but also the educational and societal contexts, as well as subjectivities (i.e. personal experience of disability, own motivations, etc.) Co-design is a method that helps to encompass all those features, but that is not easy to achieve with impaired users, especially when they are children. In the context of a research project on interactive maps for visually impaired people, we first conducted a field study to better describe potential users (visually impaired people, but also parents, teachers, therapists, etc.) and their needs. Building upon this field-study, we developed a set of design cards representing users but also needs, places, goals, etc. We then designed a workshop aiming at improving the knowledge and empathy researchers had about users, as well as the ideation step of the design process. We report on how these methods facilitated the creation of inventive scenarios, interactions and prototypes, but also how they helped researchers to think about their own design and research practices.