This design study aims to reduce the discomfort and facial trauma seen with the use of the MBU-20/P oxygen mask for fighter pilots of the Royal Netherlands Air Force. To achieve this, the following research questions are answered: •Are the reported issues with F-16 pilot oxygen mask usage still present with current F-35 fighter pilots? •Are there differences in facial features between Dutch and American fighter pilots and does this influence the fit? •Is it possible to design a better fitting mask with digital fabrication tools? The current shape of the oxygen mask is based on anthropometric research on American male fighter pilots from 1967. Since the introduction of the current oxygen mask used by the Royal Netherlands Air Force in the 1990’s, the design has not changed. No anthropometric research has been conducted on how this mask shape fits European or Dutch male and female pilots. To answer the research questions, various methods were used. Semi-structured interviews and questionnaires were conducted with F-35 pilots to identify their issues. Anthropometric research was conducted to analyze facial differences in Dutch and American fighter pilots. A virtual fit analysis algorithm was created to better understand the relationship between mask shape, facial features and discomfort. Based on these analyses a new oxygen mask design was proposed using digital fabrication techniques and the design was evaluated in flight like conditions. The results of the study showed that current F-35 pilots still experience discomfort and, in some cases, facial trauma from using the oxygen mask. The greatest discomfort was experienced on the nasal root, which is in line with literature. High G-forces and prolonged time of wearing the mask increased this discomfort, leading to adverse behavior and possible unsafe situations. Significant differences in facial features were found between Dutch fighter pilots and the American fighter pilots, on which the design is based. The current sizing system of the oxygen mask does not cover the Dutch fighter pilot population properly. The differences facial features and improper sizing system were considered to be a main contributor of the discomfort experienced by Dutch fighter pilots. The virtual fit analysis showed how the current design’s shape does not fit the facial features of Dutch fighter pilots well. By considering the pressure discomfort threshold and soft tissue thickness, better insights were generated on the fit and associated discomfort of oxygen masks. The virtual fit analysis was used together with a parametric model to quickly and iteratively redesign the oxygen mask, based on anthropometric data. These models enabled the creation of redesigns which are better suited for the facial features of Dutch fighter pilots. The redesign was evaluated through physical evaluation, production cost estimation and a reflection on requirements and wishes. The physical evaluation showed a significant decrease in pressure at the nasal root, an overall reduced pressure on the face, an improved pressure distribution and increased comfort of the redesign...