Die opening-closing means 10 includes a servo motor 11 and a movement conversion mechanism and is disposed between a support plate 8 and a base stand 1. There is connected on the power line of the battery a voltage holding circuit which is formed of a capacitor so that the variation of battery voltage slows. Each of the plurality of depressions andor extrusions comprises a top portion, a bottom portion, and a sidewall portion enclosing the top portion and the bottom portion, and at least part of the sidewall portion comprises a curve. The machine is compact, light, rigid and sized to fit through a standard doorway.