Multiple social and technological factors, such as access to digital tools or concern for sustainable development, have contributed to product design crossing the professional boundary to reach the end user. But can end-users create their own products? Some tools, such as 3D printing, have proven to be a good intermediary on the road to product design. In this sense, modular design can contribute significantly to this end by allowing the end user to intervene in the design and manufacture of their own modules. This is of particular benefit to prosumers, users who fulfill both the role of producer and consumer. This paper tests a design method focused on creating products based on modular design and aimed at prosumers. For this purpose, a two-hour design workshop is conducted with three groups of four people, all of them prosumers and novice designers. As a result, three design concepts are obtained and developed through to prototyping. After the end of the workshop, an evaluation method is applied to the three resulting concepts by the researchers in order to measure their modular and prosumer design features. This experience marks a starting point in the application of modular design by non-specialized users, contributing to the evolution towards a more sustainable consumption model that empowers the role of the end user.