The invention relates to a resilient foot insert for an artificial foot, having at least one spring element that determines the spring rigidity of the artificial foot, and an adapting device for changing the spring rigidity of the spring element. In this method, a plate-shaped first member for causing molten solder to adhere thereto is mounted on top of a heater. Further, non-discharge spaces are provided in barrier ribs formed on a rear substrate and black material layers functioning as the black stripes are formed in cavities corresponding to the non-discharge spaces.