Contextualization: Our Safety VEST Hackathon was inspired by a student’s senior project, which explored the fit of safety vests for construction workers, discovering women were disproportionately impacted by improperly fitting personal protective equipment (PPE). Goals and Methods: A feminist hackathon event was hosted and analyzed to understand wearers’ problems (especially women’s problems) with construction safety vests. The means and methods used to ensure collaboration and input from participants following feminist design principles are discussed. The goal of the hackathon was to improve the fit of PPE for varying body types by gaining insights from industry workers to address the needs of the construction’s increasingly diverse workforce. During a two-day event, six teams redesigned vests, cut them apart, and constructed prototypes, which were then presented to industry workers and vest manufacturers for feedback. Faculty and student researchers took fieldnotes and interviewed (n=16) hackathon participants. Quantitative and qualitative data, including surveys, design reflection journals, and semi–structured interviews, were collected and analyzed to conceive new design and safety features for different body types and wearer needs. Results: Building on feminist interaction design principles, our paper presents the development, implementation, and results of a design process where users were invited to participate in revisioning the safety vest to better serve their needs for safety, comfort, fit, and function. Improvements to the redesigned vest included the creation of synching cords, hoods, water bladders, identification holder pockets, length, reflective material, pocket changes, and ergonomic features to support posture and redistribute weight and tools. Final Considerations: This study expands the field of research surrounding feminist hackathon design principles by including women in collaborative design processes to understand and improve the fit of safety vests for women on construction sites and address workplace inclusion and retention.