In functional design, and particularly in mechanism design, the concepts of kinematics are applied so that the components of a mechanism are designed and produced with a certain shape, so that they perform a certain trajectory dictated by the operating requirements.

The objective is to create an optimal structure for the fulfilment of a given purpose.

The designer then determines the force required to move each element along the required path. This information helps determine the type of material to be used for each component and the mass to be added.