The only way to create a shared understanding of an idea in the design process is to convert it into a prototype. Since prototypes are in general built by experts and tested by users, we want to discover which materials users like and if experts and users are aligned in this choice in the different design phases. In this experiment, the tested object is an intangible artefact. We gathered qualitative data on how users and experts perceive low fidelity prototypes made of different materials. We found that the sequence of prototyping materials to use for each phase of the design process depends upon the user. The tangibility level of prototypes increases as the design process progresses. Less tangible prototypes works in brainstorming while ones that are more tangible are perfect for the testing phase. In general, prototypes that are more tangible facilitate creativity, interaction and communication, because they allow a direct link between actions and thoughts.