Just about everyone who drives or owns a vehicle has suffered a body dent somewhere on his car, SUV or truck. Dents can be simple and shallow, amounting to no more than a concave depression in the metal, or they can involve deep gouges, cuts and punctures. For the simple dent, a do-it-yourself repair person stands a good chance of making the repair himself, if he follows some basic steps and invests in a few specialised tools.
Park the vehicle in a well-lighted area, preferably outside. Mix a solution of dish washing soap in the bucket of water and sponge the dent area clean. Rinse with water and dry the area with a rag. You will need to get to the inside surface area of the dent, which might involve removing a door panel or reaching up under a bumper well, if you have not already done so. Place a straightedge steel ruler over the outside of the dent to gauge its depth.
Reach under the body panel and place your palm over the convex surface of the dent and shove hard. Many dents will pop back into place this way -- so use this technique first. If the dent does not move, select the smallest flathead body hammer with the shortest swinging reach that you have.
Select a dollie (the small handheld anvil) that has the best curvature profile of the outside of the dent. Hold the dollie against the dent (outside) and tap the hammer against the convex portion of the dent from the inside.
Measure the depth of the dent with the straightedge ruler to see if you have made progress. If you have, continue tapping, using increased pressure with the hammer blows until the dent pops back fully into its normal profile. Switch to a larger diameter hammer head, if you notice any smaller dents appearing in the metal.
Measure the depth of the dent again with the straight edge. If you have a raised surface now (a reverse-dent), place the dollie on the underside of the panel and tap the outside surface of the raised section with the hammer. The dent should reverse direction and fall back into its normal profile. If an elevation still remains to the reverse-dent, heat the area with a propane torch until it just starts to glow, then remove the torch. The dent should contract after it cools, and fall back into its normal shape.
For dents that have cuts, gouges and stretched metal, pound them out with the dollie and hammer as a you would for a normal dent. Then use a body file to shave the outside surface of the metal down until it remains even. For severe damage, you might have to use body putty to fill in all the minute creases and tears in the metal, then file with the body file and various grits of sandpaper. Use a drill motor and drill bits to drill several small holes into a panel that you can not access from underneath. Use a body hook tool to pull the dent outward, then use body putty and a file to level the damaged area. Do not pound the dent with extreme force. Use multiple medium--pressure taps, applying as many blow as it takes to work the metal back into its original shape.