Abstract: The article (10) comprises a central region (12) with a recessed rim (32) comprising a peripheral flat portion (14) onto which the film (40) is heat-sealed. The film used is a cold-drawable plastic film, and the process comprises in particular a step of peripheral holding and axial displacement of the film relative to the part, beyond the central region, by drawing the film in the region of the rim without any substantial external application of heat. The film is thus cold-formed to give it a concave shape with zones (42-48) associated with the central region (12) and the rim (32) of the article. The film is then held in contact with the flat portion, the whole being heated simultaneously to effect the heat-sealing.