(57) Apparatus forthe continuous extrusion of metal cladding 36 on to a thermally sensitive, continuous core 38 in which feed 34 is introduced into a circumferential groove 4 in a rotating wheel 2 to contact arcuate tooling 6 and an abutment. The feed is constrained by the abutment to flow through an orifice 8 to an extrusion chamber 10 around a hollow, open ended, portal mandrel 12 to extrude through an annular orifice 22. A shroud 26 of high thermal insulation properties, such as a braided glass fibre sleeve, is interposed between the interior of the cladding 36 and the core 32 and is of a thickness and length sufficient to limit to an acceptable rate transfer from the extruded cladding 36 of heat generated by extrusion to the temperature sensitive core 32.