The method enables the production of a final assembly (A) comprising two layers and comprises a step (100) of providing a temporary assembly (AT) comprising a temporary core (NT), a step (124) of separating the temporary assembly (AT) into a first divided assembly (AFI), a second divided assembly (AF2), a third divided assembly (AF3) and the temporary core (NT). The method comprises a step (135) of reassembling the first divided assembly (AFI), the second divided assembly (AF2) and the third divided assembly (AF3) to form the final assembly (A).