Stakeholder engagement with prototypes during the front-end phases of medical device design can support problem identification, problem definition, and early concept generation. This study examined what prototypes were leveraged to engage specific types of stakeholders during front-end medical device design. Analysis of semi-structured interviews with 22 design practitioners in the medical device industry revealed some common associations of prototype choice for particular stakeholders. A few associations are highlighted: designers engaged users with physical three-dimensional (3D) prototypes, financial decision-makers with physical 3D and two-dimensional (2D) prototypes, government and regulatory stakeholders with 2D prototypes, and expert advisors with digital 3D prototypes. The rationale provided by practitioners revealed the intentional selection of prototype form for specific stakeholder engagements.