You cannot use any type of paint on metal surfaces. Because metal surfaces do not have tiny pores like plastic or wood, normal paints do not hold on strongly to metals. But acrylic, which is a very commonly used model paint, works well on metal. However, there are ways to use other types of metals. In order to do this, first, you have to coat the surface with a primer. The primer will act as a base for the paints. Make sure the primer coating is thick enough and covers the whole surface evenly. This layer of primer will also protect the metal against corrosion.