Try to shape or fix sheet metal with just a hammer and you quickly can make one big dent into many little dents. In order to really make it flat and smooth you need a dolly on the other side. You can also use different shaped dollies to form creases, curves and more. The metal working dolly is as versatile a tool at making complex metal surfaces as an English wheel, only it works on a much smaller scale. Eastwood sells dollies in a wide variety of shapes and sizes to fit the curves of whatever you are working on. We even have serrated hammers and dollies for shrinking stretched and dented areas.