Method for smoothing and polishing metals via ion transport via free solid bodies and solid bodies for performing the method

An assembly for polishing a surface of a metal part, the assembly comprising:

• a receptacle that contains a gas;
• an electrically conductive element that is electrically coupled to a first pole of a current generator;
• a securing device inside the receptacle that is connected to a second pole of the current generator, the second pole having opposite polarity to the first pole, the securing device configured to hold the metal part during polishing;
• and
• a plurality of free solid bodies located inside the receptacle, each of the free solid bodies comprising a non-electrically conductive structure containing an amount of electrolyte liquid to cause the plurality of free solid bodies to be electrically conductive, the plurality of free solid bodies being configured to polish the metal part via ion transport, when the assembly is in use, the plurality of solid bodies being electrically coupled to the second pole.