Participatory prototyping involves users and stakeholders in actively building, adapting, and modifying prototypes rather than merely reacting to ones the design team has produced. It is an extension of co-design into the prototyping phase: the people who will use a product become active co-creators of its design rather than passive evaluators. The method produces prototypes that are more closely aligned with genuine user mental models and desires, and participants who feel ownership over the design process and its outcomes.