Wes the dry ice work lnike Koz discribed, but it dies not remove the streching that happens to the metal when dented, so there is still a slight dent there. I have also heard that the paint in these spots, due to the metal changing shape, can release and cause it to chip off. If I have insurance I would spend the extra and have it done professionally on a new or newer vehicle. If its a 1990 f-150 that you just got for $500 then I might got the dry ice method. Part of the reason is it needs to be a very hot day with the vehicle having spent a long time in the direct sun before it works.