Juan Martínez Motañés (1558-1649) was one of the most important Andalusian sculptors and a great friend of Velázquez's father-in-law and teacher, Francisco Pacheco (1564-1644).

Dressed in black, with a starched white collar, the sculptor is shown modeling a wax or clay bust of Felipe IV (1605-1665) that was to be sent, along with a painting by Velázquez, to the Italian, Pietro Tacca (1577-1640) as a model for his bronze sculpture of the Monarch, which is now in Madrid's Plaza de Oriente.

His gaze, directed at the spectator rather than at the royal bust, is a defense of the intellectual nature of sculpting. This is an allegorical device Velázquez would repeat in his self-portrait in Las Meninas (P01174).