Like any tool, the higher the quality in manufacture, the better the tool will work. Any and all of these require proper backing to prevent distortion in use. Proper set up is a must. Strength of the material is extremely important, not saying a pan lid will not work, but, it was designed as a pan lid. Well made disc is .060 thick stainless. A heavier pan bottom of stainless would be more to my idea of a substitute and the centering of the mounting hole is of importance in mounting and use. As with any tool there is a principal in application, there is experience gained by use...I would not expect an "excellence" right out of the box but you will see in first application how it works. Access to both sides of the damage yield faster more excellent results. Virtually eliminates bumping metal in many applications. Technique in use is important and learning this take a bit of time. I am not what I would call skilled, but it sure beats hammer/dolly and other shrinking methods hands down in my opinion. And, it does not take much for the friction to generate heat, careful when wiping you do not expose bare skin to just prepped surface...definite ouch conditions exist...