Abstract: A hollow spherical article having at least two substantially diametrically opposed apertures in the spherical surface, said article being of wrought metal and having been moulded by explosive forming. The article may further comprise at least two cylindrical portions, said portions being located on the spherical surface and defining said apertures. The method of forming the hollow spherical article comprises placing a tube of wrought metal into a die, positioning a plurality of explosive charges within the tube and detonating the explosive charges to expand the tube to form said hollow spherical article having two cylindrical portions which may subsequently be removed by machining.