Use a marker to draw a square or rectangle on the metal flashing. Draw a large shape for one large statement piece of wall art or several smaller pieces to create an installation on the wall. Use metal snips to cut out the shapes.
Rough up the metal surface to help prepare it for painting. Use a medium-grit sandpaper to create a textured surface. Work the sandpaper down the flashing in long, even strokes. For metals with a visible grain, always sand in the direction of the grain.
Use a tack cloth to clean up any debris left behind by the sanding process.
Place the metal faceup on a drop cloth. Squeeze craft paint or latex paint into the painting cup, or a disposable cup. Dip your paintbrush into the paint. Shake the paintbrush over the metal to splatter paint along the surface. Do the same with a second color of paint. Repeat until all of the metal squares have been painted. Allow the paint to dry completely.
Dip a foam brush into clear polyurethane. Coat the surface of the painted metal with the clear finish. Allow it to dry completely.
Mark the wall where the finished metal paintings will hang. Mark each center point with a pencil X or dot. Hold the metal painting to the first X.
Hammer a nail into each corner of the metal painting. Repeat until all of the metal paintings are hung on the wall.