The project began with the selection of an already developed sole, rather than designing a custom one. Producing a new sole involves very high costs, which were not feasible within the scope of this project. Specialized sole companies regularly release new models from which clients can choose. Although several companies may use the same sole, a brand with a limited collection cannot afford to invest in the development of a new sole specifically designed for a particular shoe or brand, as the cost would not be justifiable. For this project, a sole from the company Bolflex was selected. Bolflex is one of the largest sole manufacturers in Portugal, offering a wide range of models in numerous colours and, most importantly, a broad selection of sustainable material options. The company operates entirely on renewable energy, including its production department. This is a significant advantage for brands looking to reduce the environmental impact of their footwear. In addition, Bolflex offers clients the possibility of recycling (upcycling) soles by grinding them down and reusing the material to produce new ones. This means that this footwear component can now be produced in a closed-loop system, with minimal loss of raw materials.