The collaborative projects of innovation have been strongly developed for twenty years. Despite this, the processes operating to co-create value remain poorly understood. The same applies for the relationships that allow their actors to make emerge progressively this value. This article aims at providing answers to these questions by studying a project driving transition towards the circular economy. My participation in a collaborative project, dedicated to recycle used garden market plastic films, allows me to provide several inputs. Firstly, I emphasize the importance of linking the relational and cognitive dimensions of value co-creation in order to better track its emergence during a collaborative project. Secondly, I propose a generic model of value co-creation process and I demonstrate how actors share resources in order to develop promising intermediary outcomes. Thirdly, I present a typology of possible value co-creation results. JEL Codes: O32, O33, L20