The metal powder can be mixed with PU Resin. This mixture is then painted into the mould as a first layer or gel coat. It is then either filled solid with resin and filler or laminated with glass fibre. When polished to reveal the metal, the castings are almost identical in appearance to a cast piece in the chosen metal. The metal content of the metal / resin mix should be as high as possible; too little metal filler is as bad as none at all.