See last 10 seconds for a speed up version.
My buddy picked up an air pressure dent repair kit. You cap one end with a inlet valve, and the other end with an emergency pressure valve. The idea is to fill the pipe with compressed air, but not enough to get the valve to go off. Then heat the pipe to soften the metal and allow the dent to pop out.
In practice there are two things that make this difficult to do, the first is the seals are limited use. You essentially need a new seal every few pipes because of leaks. The second is the emergency blowoff valve is a bit too sensitive. It blows off around 100psi.
Other then that, it works pretty well, but I think we can improve the set up.
