Repair a dent in an aluminum door by washing the dented area, applying heat to the area using a sheet of aluminum foil as a buffer and then quickly cooling the area using a can of air or air from a compressor. The dent pops out as it cools.
Use a heat gun or hair dryer to apply heat to the dented area for the best results. It may take up to 30 seconds during the cooling stage using compressed air for the dent to return to its original shape. Another way to repair a dent is to use a rubber mallet to pound the dent out gently from the side of the door where the dent creates a convex shape. A hammer with a block of wood in between it and the door is an acceptable substitute for a rubber mallet.