The project entitled “DIY, Plastic Goodbye!” was born from a shared observation among all partner organisations that plastic pollution is a global issue directly affecting our territories, whether urban, rural, coastal, or island-based. Beyond raising awareness of this environmental challenge, we wanted to enable young people to better understand their role in the ecological transition and provide them with the means to take concrete action at their own level. Our main objective was to help participants become aware of the consequences of excessive plastic consumption while showing them that everyone can contribute to changing practices, both in their daily lives and within their communities. To achieve this, we chose an approach based on non-formal education, experiential learning, and intercultural exchange, allowing young people to develop their own reflections through practical, real-life situations. The project was designed around two complementary mobilities. The first, organised in Marquixanes, aimed to lay the foundations of the project by enabling participants to understand the issues related to plastic pollution, discover the practices of each partner country, and begin imagining shared solutions. The second mobility, organised in L’Étang-Salé on Réunion Island, made it possible to deepen these learning experiences in a very different context—that of a European island territory directly confronted with the challenges of protecting the oceans, preserving biodiversity, and managing waste. The continuity between these two exchanges formed a genuine common thread throughout the project. We also sought to develop the participants’ competences through participatory methods. The activities were designed to strengthen their creativity, their ability to work as a team in an intercultural environment, their sense of initiative, their communication skills, and their capacity to design projects addressing concrete challenges. The project also pursued an objective of inclusion. Particular attention was paid to the participation of young people with fewer opportunities, especially those facing geographical, economic, or educational barriers. For many of them, Erasmus+ represented their first experience of international mobility. We wanted to offer them the opportunity to experience this in a supportive environment that fostered self-confidence, encounters with other cultures, and openness to new perspectives. Finally, the project aimed to promote the values and opportunities offered by the Erasmus+ Programme while strengthening participants’ active citizenship. Beyond the two mobilities, our ambition was for the young people to continue their engagement within their local communities by implementing awareness-raising activities and acting as multipliers among other young people. We wanted this experience to become a genuine starting point for long-term commitment to environmental protection and European cooperation.