"For keeps" is right! Years ago I was helping a friend model a cam at the heart of a large piece of metals processing equipment for these guys: https://www.but

"For keeps" is right! Years ago I was helping a friend model a cam at the heart of a large piece of metals processing equipment for these guys: https://www.butechbliss.com https://www.butechbliss.com It was _almost_ right, but had a negative curvature on one surface. The effect was to lift a multi-ton piece of machinery off the floor – which it was bolted to. My understanding is that the cam is now used as a coffee table!