I have been lost on YouTube watching videos on this subject and it is absolutely amazing. There are a whole bunch of videos on this subject and the results these guys are able to attain is just incredible. Gas tanks that I would've thought would require a complete stripping and major repair are saved. With very specialized tools. I also found it very interesting the way they use heat to make the metal more malleable and also the use of specialized lights to see curvature reflections. I hope you find this as interesting as I did. It makes me think of the way I once lived with an otherwise perfect gas tank on a Triumph I owned that had a big dimple in the tank from a tip over. Here are just two of many videos.