Easy fix for dented bumper?

[Numo]

I used a heat gun to help pop out a dent in my bumper once - I'm not sure a hair dryer would generate enough heat to do it. However, you have to be very careful not to get the gun too close to the paint, or it will blister. I also had to apply leverage from in concave side, but I can't remember what I used for that. I like the football idea, but again, that may not be enough to do the trick.