Abstract: A hollow body is formed from several multi-layer plastic elements which are welded together and comprise a barrier layer that is a barrier to liquids and to gases. The elements form an appendage which extends from an outer surface of the hollow body, wherein the appendage comprises two multi-layer plastic layers, each of the two layers having a respective barrier layer. A method for manufacturing the hollow body includes using compression moulding in a multi-part mould comprising welding kerbs. When the mould is being closed, at least the barrier layers of the multi-layer plastic elements are forced to flow into a shallow slot formed between the welding kerbs of the closed mould. A multi-part compression-blow-moulding mould comprises welding kerbs which, when the mould is closed, form a slot or space between them with a height of cross section that decreases towards the outside of the mould and which is extended by a shallow and broad slot intended to compress the plastic.