Originally Posted by repechage

Pretty darn close is not good enough for Metacortex.

Tubes and lugs, even investment cast lugs and modern tubes are not that precise.
Buy a tube set and roll them on a surface plate. Is there a problem if they are not perfect?
Consider that many are post forming heat treated, actually I would expect it.
Now, what do you do, keep ordering more sets? No, you mark the bow and set that along the centerline of the bike.
Now you have to decide how you are going to miter this tube, to the "drawing" or to what exists, keeping you design goal in mind.
Are the 73° lugs you ordered, actually 73°? Material shrinks in the cooling process, due to the shape, they may not be… decision time.
My assertion is that after you have built a few you will understand that and where "letting things go" is better.
Not for the design important attributes, but for elements that do not matter.

If you fight the material, you may not keep what you fought for later in the build.
Framemaking is sort of like blacksmithing, but with calipers.