A method of manufacturing a composite wall with an open cell metal foam core layer bonded to an inner cladding layer and an outer cladding layer. The method involves: creating a core substrate of open cell gas permeable foam in a chosen shape; impregnating the open cell foam substrate with metal vapour and depositing a porous layer of metal on exposed internal and external surfaces of the substrate thereby forming the open cell metal foam core through metal vapour deposition; and forming the inner and outer cladding layers upon the metal foam core through spray application of metal or ceramic.