Method for producing metallic micro-pieces including at least two parts of which at least one part being obtained by photolithography and electroforming, this method comprising at least the following steps: A) assembling on a conductive support at least one plate made of insulating or conductive material comprising a plurality of through cavities, said cavities including a structured inner wall comprising a thread or a combination of at least one horizontal bearing with a thread or a combination of at least one vertical or oblique side with a thread B) depositing a photoresist layer on the plate, irradiating and polymerizing by means of a photo mask, including a plurality of patterns, so that said patterns entirely cover each cavity and at least one area in the proximity of each cavity in contact with said cavity, eliminating the non-polymerized photoresist layer in order to obtain a plurality of mixed cavities (3, 7), each mixed cavity (3, 7) including a first level formed by the cavity of the plate and a second level formed by a through cavity in the photoresist layer, each cavity of the second level being positioned above each cavity of the first level so that the perimeter of each cavity of the second level includes the perimeter of each cavity of the first level, or B') depositing a photoresist layer on a conductive support, irradiating and polymerizing the photoresist layer by means of a photo mask and eliminating the non-polymerized photoresist layer, the remaining photoresist layer forming a plurality of through cavities, A') assembling on the conductive support covered by the photoresist layer at least one plate made of insulating or conductive material comprising a plurality of through cavities, said cavities including a thread or a combination of at least one horizontal bearing with a thread or a combination of at least one vertical or oblique side with a thread, in order to obtain a plurality of mixed cavities (7a, 3) each of them including a first level formed by a through cavity in the photoresist layer and a second level formed by the through cavity of the plate, each cavity of the second level being positioned above each cavity of the first level so that the perimeter of each cavity of the second level includes the perimeter of each cavity of the first level, C) depositing a metallic layer (9a, 9b) by electroforming in each mixed cavity (3, 7) in order to fill the first and the second levels, D) machining the metallic layer (9a, 9b) to a predefined thickness by a mechanic process, eliminating the polymerized photoresist, E) extracting the metallic layer (9a, 9b) of each cavity of the plate and of the conductor support and obtaining a plurality of micro-pieces including two superposed parts formed by the levels of the mixed cavities (3, 7). A) assembling on a conductive support at least one plate made of insulating or conductive material comprising a plurality of through cavities, said cavities including a structured inner wall comprising a thread or a combination of at least one horizontal bearing with a thread or a combination of at least one vertical or oblique side with a thread B) depositing a photoresist layer on the plate, irradiating and polymerizing by means of a photo mask, including a plurality of patterns, so that said patterns entirely cover each cavity and at least one area in the proximity of each cavity in contact with said cavity, eliminating the non-polymerized photoresist layer in order to obtain a plurality of mixed cavities (3, 7), each mixed cavity (3, 7) including a first level formed by the cavity of the plate and a second level formed by a through cavity in the photoresist layer, each cavity of the second level being positioned above each cavity of the first level so that the perimeter of each cavity of the second level includes the perimeter of each cavity of the first level, or B') depositing a photoresist layer on a conductive support, irradiating and polymerizing the photoresist layer by means of a photo mask and eliminating the non-polymerized photoresist layer, the remaining photoresist layer forming a plurality of through cavities, A') assembling on the conductive support covered by the photoresist layer at least one plate made of insulating or conductive material comprising a plurality of through cavities, said cavities including a thread or a combination of at least one horizontal bearing with a thread or a combination of at least one vertical or oblique side with a thread, in order to obtain a plurality of mixed cavities (7a, 3) each of them including a first level formed by a through cavity in the photoresist layer and a second level formed by the through cavity of the plate, each cavity of the second level being positioned above each cavity of the first level so that the perimeter of each cavity of the second level includes the perimeter of each cavity of the first level, C) depositing a metallic layer (9a, 9b) by electroforming in each mixed cavity (3, 7) in order to fill the first and the second levels, D) machining the metallic layer (9a, 9b) to a predefined thickness by a mechanic process, eliminating the polymerized photoresist, E) extracting the metallic layer (9a, 9b) of each cavity of the plate and of the conductor support and obtaining a plurality of micro-pieces including two superposed parts formed by the levels of the mixed cavities (3, 7).