Think of how they build bridges or ships. Do you think they have fancy CNC'ed jigs? Pfah.
A summer as a helper in the Nashville Bridge Plant in Bessmer, AL is the reason I finished college; anything to not end up back there.Car reamer/Bridge reamer
As one end of a two-man reamer, up on a scaffold, two bridge sections were joined together, tongue and groove. The holes had been left purposely undersize. We'd pin the sections with drifts, then ream all the holes through three plates to alignment. The riveting crew would come behind riveting them together. Pull the drifts, ream those holes and good to go.
You haven't worked until it's more than 100-degrees, the humidity is near 100-percent and there's a riveting forge at your elbow.