A product platform is the set of subsystems shared across products offered by a firm. The problem of designing a product family based on a platform is formulated as an optimization exercise, from which a practical implementation is derived. The implementation consists of teams developing candidate concepts, a platform team then using these to form a platform, and finally the teams redesigning, making use of the platform. The result is a set of candidate product families: both the shared platform and the individual portions of each variant. These candidate designs may all be feasible, but they will likely have different attributes in several dimensions, such as technical performance, risk, costs, etc. The designers must then trade off design choices for the platform and the variants to determine an adequate overall family result. The procedure is illustrated by the conceptual design of JPL spacecraft making use of different telecommunications platforms.