Model is a term describing the external form of an instrument – the size and outline of the body as well as the arching of the belly and the back. The term can be used in connection with a specific master luthier (for example, the Stainer model) or refer to particular features of an instrument (for example, large model or highly arched model). Stradivari’s work over time may be used to illustrate the evolution of different body models. The numerous instruments and workshop tools that have been preserved to this day allow us to make a chronology of Stradivari’s development steps and to draw a comparison between the different models.