I have, with a fair degree of success, managed to restore some faux woodgrain panels (woodgrain print over metal) that were peeled or worn off. First, I smooth all the panel by sanding with 320 grit. A metal primer is next. Depending on the original pattern, I spray a basecoat of dull yellow or light gray. Next, using acrylic artist colors and a damp sponge, I apply the black and red colors to the sponge, and begin to streak the acrylic across the base color. By streaking it just right, it does take on the appearance of woodgrain. (you'll need to practice at this for a while on a scrap of metal) When the desired grain pattern is achieved, I take dark brown paint thinned about 300% (like water) and spray light coats over the existing panel until it looks just like wood. The final touch is to spray a urethane clear-coat over it.