Despite the spread of new circular materials and digital technologies, designers’ awareness of how to practically implement them is not fully achieved yet. Therefore, new ways to foster digital craftsmanship skills and experiential knowledge should be implemented. This contribution aims to reflect on digital technologies, especially 3D printing, in speculative design approaches with circular materials through the development of the materials library from the FiberEUse research project. This “materials and product library system” is an adaptive experiential tool that goes beyond merely collecting physical materials samples. It also includes possible products, speculative applications, and non-textual content, merging physical and virtual learning experiences. Its physical section comprises a materials library with flat samples of the materials and a product library with applications or cut-offs of some meaningful details of products. By analyzing the library’s development path, three incremental phases emerge in terms of interaction with circular materials and 3D printing for speculative approaches: experiencing materials, technology, and products. The first phase aims to preliminary explore the potential and qualities of materials through traditional craftsmanship skills. The second phase deals with the first experimentations with the technology, understanding the limits and influence on the expressive-sensorial qualities. The third phase is oriented toward new applications, investigating the possible outcomes from a formal point of view. As a synthesis, the tinkering process emphasizes the active role of experiential tools in spreading the use of circular materials and digital technologies, helping acquire new skills through an experiential approach. It also adds a further level to the exploitation of materials libraries, paving the way for new possible uses, i.e., distributed replication, participation, and implementation. As a result, materials libraries assume a more active role in the experiential knowledge transfer even during their development, representing a practical path to building new skills. Hence, a new model of materials libraries may emerge as a replicative learning and speculative design tool
