B2B product managers must test options for new offerings early in their evolution. Prototype development is a key activity in the design phase of the Forrester Product Marketing and Management (PMM) Model. Developing a prototype helps align internal stakeholders on the product concept and validate the concept with customers. Selecting the right prototype approach depends on the prototype’s purpose, the type of product, and the resources available. This report explains how to determine the right format for a product prototype, what elements to include, and how to involve key stakeholders in its creation.