A method for manufacturing an object having a polymer part, including inserting a core through a movable element via a hole passing through the movable element, inserting the polymer part in a mould, inside which the movable element is arranged, so that the polymer part is in contact with the movable element on a first side of the movable element, displacing the movable element in the mould by exerting a force, originating from the polymer part, on the movable element in such a way that the movable element slides along the core, the movable element constraining, at an entrance of the hole on the first side, at each instant and as the movable element is displaced, the position of the portion of the core in the course of being covered with polymer at this instant.