To do airbrush art on nails you will need nail art stencils or nail art masks. The nail art masks are reusable masks that have an adhesive that does not leave any residue on the nails. Of course if you are really creative and very good you can freehand the airbrush art right onto the nails. If not then take the time and invest in nail art stencils and masks. Secondly you are limited to only creating designs based on the stencils that you can get your hands on. While these stencils can greatly aid you in your airbrush art, they also can hinder your creativity. So the best way to deal with having you use stencils and reduce costs as well as leaving your creativity open is to create your own stencils. Derive inspiration from various sights around you and incorporate them into one great piece of art. See two kids on a seesaw at the park? Turn those two kids into angels on a seesaw cloud in the sky. See a couple of kids playing ball? Then turn them into angels and the ball into a cloud. Now put all of this into one art design. Metal should be wet sanded to give a rough grainy effect. This rough grainy effect will help the paint to adhere to the metal. With metal actually being smooth the paint will have a hard time sticking to the smooth surface. This is why it is important to wet sand the metal first. A base coat should be applied to the metal before any airbrush art design is started. Since with the larger dot pattern you are able to spray more areas in less time. Airbrushes also come in single and dual action. This refers to how the airbrush functions. With single action only the air is controlled with the trigger. The trigger will control the air and the amount of paint that comes out is determined by the needle adjustment on the back of the airbrush handle. The air cap and head assembly are on the front of your airbrush and they cover the tip of the needle. The purpose of these parts is to control atomization of the paint spray. Should these parts become dented or damaged in anyway you should replace them immediately. Damage to the air cap and head assembly will effect the performance of your airbrush.