Assembly defining a chamber for an active material and method for manufacturing such an assembly

A method for manufacturing an assembly comprising a tubular body and a breathable insert configured to be attached inside the tubular body so as to define a chamber for an active material in an internal volume of the tubular body, the tubular body comprising a transverse wall and a lateral wall, the breathable insert comprising a base wall and a side wall having an open end on an opposite side from the base wall, the chamber being delimited by a bottom part of the tubular body including the transverse wall and being closed by the breathable insert having its open end turned toward the transverse wall, the side wall of the breathable insert comprising a mechanical holding portion configured to cooperate by surface interference with a corresponding mechanical holding portion of the lateral wall of the tubular body, wherein the method comprises steps of:

• filling at least part of an internal volume of the breathable insert with an active material;
• inserting the filled breathable insert in the tubular body, with its open end turned toward the transverse wall of the tubular body, until the breathable insert is anchored relative to the tubular body by surface interference resulting from mutual engagement of the mechanical holding portions, wherein, in an anchored configuration, the sidewall of the breathable insert and lateral wall of the tubular body cooperate by cylinder-in-cylinder friction without undercut, and a continuous peripheral seal is formed between the breathable insert and the tubular body.