The present invention relates to a method for the production of bodies in plastic comprising two portions hinged to each other by a single rotation pin. The method comprises the steps: a) predisposing a mold with two distinct forming chambers for the two portions the mold comprises a third chamber for the single pin, made and positioned in such a way that the pin is formed already aligned along the hinge axis the mold is provided with a pair of pegs axially distanced from each other to form the third chamber and sliding along the axis between a first and a second operating position b) positioning the pegs in the first position c) injecting plastic material inside the chambers d) shifting the pegs from the first to the second position, bringing the pin to engage inside the seats e) opening the mold and extracting the two assembled portions.
