A method for producing parts formed by at least two elements (41,44) wherein the method comprises: - producing a first element by a method of producing first elements of polymer in a first mould comprising a first mould portion and a second mould portion movable relative to the other, the method comprising the steps of: ∘ closing the first mould in a first position in which the two mould portions form at least one first injection cavity connected via the first mould portion to a material injection device, ∘ injecting material into the first injection cavity to form a first element, ∘ moving one of the mould portions relative to the other, the first element remaining connected to the second mould portion, ∘ closing the first mould in a second position, in which the two portions form: ▪ at least one second injection cavity connected via the first mould portion to the material injection device, and ▪ a first solidification cavity in which the first part is placed, ∘ injecting material into the second injection cavity to form a second part in the second injection cavity and simultaneously solidifying the first part placed in the first solidification cavity, - simultaneously, producing (302, 304, 306, 312) a second element in a second mould, the second element having a lower solidification time than the first element, and - assembling the first element and the second element, wherein the first mould portion comprises at least one injection zone and at least one solidification zone, and the second mould portion comprises a first ejection zone and a second ejection zone, so that: - in the first position: ∘ the injection zone and the first ejection zone form the first injection cavity, and ∘ the solidification zone and the second ejection zone form a second solidification cavity, or the second ejection zone is positioned so as to allow ejection of a solidified part connected to the second ejection zone, - in the second position: ∘ the injection zone and the second ejection zone form the second cavity, and ∘ the solidification zone and the first ejection zone form the solidification cavity, wherein the first mould portion comprises a plurality of injection zones and a plurality of solidification zones, and the second mould portion comprises a plurality of ejection zones. - producing a first element by a method of producing first elements of polymer in a first mould comprising a first mould portion and a second mould portion movable relative to the other, the method comprising the steps of: ∘ closing the first mould in a first position in which the two mould portions form at least one first injection cavity connected via the first mould portion to a material injection device, ∘ injecting material into the first injection cavity to form a first element, ∘ moving one of the mould portions relative to the other, the first element remaining connected to the second mould portion, ∘ closing the first mould in a second position, in which the two portions form: ▪ at least one second injection cavity connected via the first mould portion to the material injection device, and ▪ a first solidification cavity in which the first part is placed, ∘ injecting material into the second injection cavity to form a second part in the second injection cavity and simultaneously solidifying the first part placed in the first solidification cavity, ∘ closing the first mould in a first position in which the two mould portions form at least one first injection cavity connected via the first mould portion to a material injection device, ∘ injecting material into the first injection cavity to form a first element, ∘ moving one of the mould portions relative to the other, the first element remaining connected to the second mould portion, ∘ closing the first mould in a second position, in which the two portions form: ▪ at least one second injection cavity connected via the first mould portion to the material injection device, and ▪ a first solidification cavity in which the first part is placed, ▪ at least one second injection cavity connected via the first mould portion to the material injection device, and ▪ a first solidification cavity in which the first part is placed, ∘ injecting material into the second injection cavity to form a second part in the second injection cavity and simultaneously solidifying the first part placed in the first solidification cavity, - simultaneously, producing (302, 304, 306, 312) a second element in a second mould, the second element having a lower solidification time than the first element, and - assembling the first element and the second element, - in the first position: ∘ the injection zone and the first ejection zone form the first injection cavity, and ∘ the solidification zone and the second ejection zone form a second solidification cavity, or the second ejection zone is positioned so as to allow ejection of a solidified part connected to the second ejection zone, ∘ the injection zone and the first ejection zone form the first injection cavity, and ∘ the solidification zone and the second ejection zone form a second solidification cavity, or the second ejection zone is positioned so as to allow ejection of a solidified part connected to the second ejection zone, - in the second position: ∘ the injection zone and the second ejection zone form the second cavity, and ∘ the solidification zone and the first ejection zone form the solidification cavity, ∘ the injection zone and the second ejection zone form the second cavity, and ∘ the solidification zone and the first ejection zone form the solidification cavity,