"Interestingly this is exactly the same issue I ran into when experimenting with inlay work."
Yes. In face to face discussions I've used the inlay example to get people to understand what I was wanting to accomplish. I've disguised my real goal because I didn't yet want "the world" to know what I was doing, AND, because I thought the "puzzle" analogy would cut to the chase. What I'm really doing is trying to kick off a small business using my CNC router to make foam tool mats. It begins with a wrench lying on a light box with a camera perched above. So that gives you an exact silhouette of a wrench. Mechanics would struggle to get the wrenches in and out of such a perfect fit. So I needed some way to dial in a "factor" as needed. Some wrenches might be adequately lose with 0.010" wiggle room while others might need twice that (or more). So I needed a solution that would solve more than one situation. Hopefully Les (Mr. SheetCam) has told me how to make it happen.