Well I built a bumper with it.so yes to bumpers. I have heard stories of improper built cages coming apart on roll overs and pieces of the cage actually killing people from stabbing inside them. Can this welder build a roll cage, Yes, But if you are not a expert welder DONT DO IT. A welder is only good as the person is using it. Ive seen people with a 70 dollar stick welder do some damn nice work.
For bumpers,sliders, repairs and what not, this welder is just fine.