A method and apparatus for manufacturing a multilayer powder blank, and the product of such manufacture which is suitable for subsequent extrusion. A hollow cylindrical container with its central axis oriented horizontally is rotated while powder is allowed to fall from a powder distribution tube in the center of the container downward onto the inner surface of the rotating wall, thereby forming successive layers of powder which are maintained in position by centrifugal forces acting thereon. The powder blank consisting of the multiple layers is removed from the container, isostatically compressed, and finally sintered, with fusion of the outer powder layers into a fused, water-tight coating.