My work on tangible interaction began with the exploration of the possibilities of digital pen and paper in various fields, such as augmented laboratory notebooks for biologists, interactive scientific datasheets, augmented scores of composers, augmented strips of air traffic controllers and job cards for aviation maintenance. Through each of these projects, the focus was first to understand why paper/pen devices and their very diverse properties particularly well align to the associated activities, and then to participatory co-evolve these devices by moving to mixed and digital properties. Based on our work with Air traffic Controllers, I have also contributed to the reflection on tangible interaction models, by putting into perspective distributed cognition processes such as externalization and the use of interactive paper strips on the stripboard. Currently, I work on meteorological visualization for the pilots undergoing rapidly developing thunderstorms, and I reflect on the physical design space for situation awareness and performance in the interactive cockpit, where touch technologies are going to replace current electronic displays for flying and navigating instruments. My complementary experience in industry and research has also allowed me to pursue a reflection on software development processes. During my thesis, I have observed and analyzed the programing practices of biologists in the context of a biology research institute - the Pasteur Institute - and proposed a process paradigm: participatory programing. I now focus on the quite different context of system engineering in aerospace, when applied to interactive system design and teaching. In this context, participatory design brings to industrial processes - strongly based on models - an opportunity for early validation and maintaining consistency among multi-disciplinary stakeholders all along the process.