Eric von Hippel, professor at MIT Sloan and a pioneer of user-innovation theory, examines how people with lived experience of substance use disorders are designing their own tools and interventions to fill gaps left by formal addiction treatment systems. Co-presented with Hanna Adeyema as part of MIT's RES.SUD-01 Substance Use Disorders Ventures Program, the session applies von Hippel's long-running research on user innovators, originally developed in fields like software and sporting equipment, to recovery and harm reduction. The talk covers examples of peer-built solutions, discusses why users rather than professionals often spot unmet needs first, and considers how these grassroots innovations might be identified, supported, and scaled into ventures. It runs as the second session of the course, aimed at students and practitioners interested in the intersection of innovation studies and addiction support.