A method for making arms for spectacles from composite material with differentiated rigidity, the following features being defined on the arm: - a predominant longitudinal direction; - at least a first portion of the arm; and - at least a second portion of the arm, adjacent to the first portion along the longitudinal direction and having lower flexural rigidity than the first portion, - at least a third portion adjacent to the first portion and placed on a side longitudinally opposed to the second portion, this third portion having lower flexural rigidity than the first portion, the method comprising the steps of: - providing at least a first layer of non-cross-linked fibre-reinforced polymer material, the at least one first layer extending along the predominant longitudinal direction at least at the first, the second and the third portions; - providing a separating element at the first portion, and - superimposing at least a second layer of non-cross-linked fibre-reinforced polymer material on the at least one first layer, the second layer extending along the predominant longitudinal direction so as to cover the separating element at the at least one first portion and so as to be in contact with the at least one first layer at the at least one second portion and at the at least one third portion; - subjecting the at least one first layer, the at least one second layer and the separating element interposed between them to a moulding process at predetermined pressure and temperature levels, so as to cross-link the polymer of the composite material, thus obtaining a thickness and rigidity of the arm at the first portion which are greater than the thickness and rigidity of the arm at the second portion and at the third portion. - a predominant longitudinal direction; - at least a first portion of the arm; and - at least a second portion of the arm, adjacent to the first portion along the longitudinal direction and having lower flexural rigidity than the first portion, - at least a third portion adjacent to the first portion and placed on a side longitudinally opposed to the second portion, this third portion having lower flexural rigidity than the first portion, the method comprising the steps of: - providing at least a first layer of non-cross-linked fibre-reinforced polymer material, the at least one first layer extending along the predominant longitudinal direction at least at the first, the second and the third portions; - providing a separating element at the first portion, and - superimposing at least a second layer of non-cross-linked fibre-reinforced polymer material on the at least one first layer, the second layer extending along the predominant longitudinal direction so as to cover the separating element at the at least one first portion and so as to be in contact with the at least one first layer at the at least one second portion and at the at least one third portion; - subjecting the at least one first layer, the at least one second layer and the separating element interposed between them to a moulding process at predetermined pressure and temperature levels, so as to cross-link the polymer of the composite material, thus obtaining a thickness and rigidity of the arm at the first portion which are greater than the thickness and rigidity of the arm at the second portion and at the third portion.