This is an afternoon project for those with access to the right tools. There are dent-pulling kits available that use suction cups or hot glue, avoiding the need to drill a hole into the dent. If you want your car to look like new, though, consider a trip to the auto body shop.
Borrow a dent-pulling tool (looks and acts like a slide hammer), a dolly (a tool designed especially for flattening and shaping metal) and a metalworking hammer.
Find the center of the dent and drill a hole in it using a 1/8-inch (3 mm) drill bit. (Or, using the hot glue gun that comes with some kits, glue the plastic adapter to the center of the dent.)
Thread the dent-pulling tool into the hole you just drilled (or attach the dent-pulling tool to the plastic circle you just glued on). Pull on the dent-pulling tool to flatten or pop out the dent.
Hammer the front of the dent with the metalworking hammer while holding the dolly against the back of the dent. You may need to get underneath the car or open the hood or the trunk to reach the back of the dent.
Using a medium surface-conditioning disk on your drill, grind all the paint down to bare metal extending at least 1 inch (2.5 cm) around the dent. Fill the entire area with body filler.
Let the filler dry, then sand with sandpaper wrapped around a block of wood. Start with 36-grit sandpaper and work your way down to 120-grit.
Prime the area with spray primer for cars. Apply six coats, letting primer dry between coats.
Sand the primer with 600-grit wet-and-dry sandpaper to remove any scratches. Touch up the area with matching car paint. Re-sand and repeat if paint is not smooth.
