The present invention concerns a mechanical method for generating nanostructures in order to obtain on a surface of a metal piece a nanostructured layer of defined thickness. A quantity of perfectly spherical balls (22) are disposed in a chamber that is closed for the size of the balls. At least one of the walls of the chamber supports or constitutes the piece to be treated (10). A vibrating motion is imparted to the chamber in a direction perpendicular to the plane of the circular motion of the chamber supporting or constituting the piece to be treated. The speed of the circular motion and the frequency and amplitude of the vibrating motion is determined based on the physical properties of the balls so as to communicate to the latter sufficient kinetic energy to create nanostructures on the material of the piece treated by impaction of the balloon surface of the piece.