7 Three dimensional (3D) printers; parts, fittings and accessories specially adapted for three dimensional (3D) printers; apparatus for electric welding; apparatus for mechanised welding; arc welding apparatus; electrical arc welding machines; electrical arc welding apparatus; machines for welding, electric; metal welding apparatus, electric; metal welding machines, electric; robotic electric welding machines; robotic electrical welding apparatus; robots for welding; welding apparatus, electric; wire welding machines; apparatus for printing, machine; printing machines; printing machines for printing on product substrates; robotic three dimensional (3D) printers