Method of manufacturing consumable filler metal wire, rod, or stick, and the like, of predetermined length and cross-section for use in welding, including: providing an ingot of a first metal and one or more different further metals; forming composite product by providing the ingot of the first metal with one or more hollow cores in substantially parallel relation to each other and locating in the hollow cores the different further metal or metals; applying pressure to the composite product to reduce its cross-section to a predetermined cross-section to form feedstock. Optionally further deforming the feedstock by mechanical pressure to form wire, rod or stick, of final cross-section so ultimate alloying of the first metal with the different further metal or metals occurs when the wire, rod or stick is used as filler material or consumable electrode during welding. Using this filler metal for welding an assembly of aluminium members.