It may be splitting hairs, but I think certain changes to hammers must qualify as invention, certainly, including the crosshatch innovation, the material science involved for both fiberglass and titanium handles, and the improved weight distribution. It's not clear to me what would be considered a complete reimagining of the hammer, as a hammer is such a broad category of tool. Is a mallet a hammer? When I smack something with the backside of an impact driver, is it a hammer? I sure use wrenches as hammers occasionally.
So, what's the line between inventing and refining?
So, what's the line between inventing and refining?