A tool with a driver, a motor, a structure to which the motor is coupled and a return cord assembly. The cosmetic case opens a discharge port of a main body by a support unit that is pushed backwards when a puff is pressed, and closes the discharge port when the puff is released, thus stopping discharging powder. The method includes starting a personal-authentication application on the personal-mobile device in response to receiving the first communication, and receiving in the personal-authentication application a user verification for confirming logging into the account. The acknowledgment method provides for detection of errors over the wireless link, the selective acknowledgment of error-free transmissions and the selective resending of transmissions received in error. A shredding rotor of the shredding assembly may include at least one brace including at least one leg extending outwardly from the outer surface of the rotor.