wow you really are a physics ta
youve got no sense for reality :p ;)
gimme a break though, machines might be nice and repeatable, but just because its a CNC machine doesnt mean the process isnt prone to mistakes
coming from a strong machining background and lots of precision hand layout and jigging its definitely possible with the right tools, methods, and techniques to hand layout an entire jig pattern to within .003 without much trouble. I did this routinely for points in three dimensionsins spanning FEET, and not just 300mm over a 2d FLAT surface. .003" is the thickness of a standard sheet of paper and i can assure you that makes no practical difference in a ski mount