The present invention relates to a method for welding together two layers (1, 3), or work-pieces, within a multi-layer assembly (1, 2, 3). The present invention provides a method in which laser light (4) is directed through an outer layer (1) of the assembly, allowing transmission of the laser light from its outer surface to at least within the vicinity of its inner surface substantially without any absorption of energy from the laser light, towards a layer (3) comprising an absorbent component (7), corresponding to a portion thereof, capable of absorbing laser light within a given wavelength range thereby creating a welded area (6) between a surface of the layer (3) comprising the absorbent component (7) and a surface of a layer (1) facing the layer (3) comprising the absorbent component (7). The absorbent component (7) can be provided either within the bulk of a layer or it can be provided as a separate surface-layer on one or both surfaces of a layer. The invention also provides specific products manufactured using the concept of the present invention.