Abstract: The impressions are produced using an original plate (19) bearing a design by the following steps: a plastic plate (4) made of thermodeformable material is prepared and placed, in an adjusted position corresponding to the location of the first impression to be produced, between an electrode (7), the outline of which corresponds to the periphery of the design and which is surrounded by an insulating border (24), and the original plate (19) which forms a second electrode; the first impression is produced on the plastic plate (4) by high-frequency heating of the plastic plate (4) via the electrodes, and by compression; the plastic plate (4) is then cooled, the original plate (19) is separated from the plastic plate (4) that is displaced successively in the other adjusted positions corresponding to the other impressions to be produced and, in each position, the heating, compression and cooling steps are repeated in order to reproduce the next impression.