The rear of the chassis originally had the most twist and dimensionally bore little resemblance to the drawings.
New tubes were cut, from heavier gauge steel and then welded into place.
By entering all of the design into CAD first, it was simply seconds to gain any position in 3 planes. This would not be possible with paper drawings without hours of trigonometry. I cannot recommend using CAD drawings enough, I’d say they were essential.
Using this method was initially extremely slow, but as the number tubes grew, the time for each tube dropped considerably. We were surprised that by using this method, we were often less than 0.5mm out, on dimensions not initially marked on drawings.
Tools that I found definitely worth the investment, were digital angle finding protractors and digital spirit levels (available cheap on Fleabay). Other much simpler and traditional devices such as large internal and external calipers were an almost instant way of comparing dimensions.