I ran a medium sized machining co. From the late 80's until the early 2000's. We had around 60 machine tools.
The co. had been in operation from the late 40's and had examples of the history machining from 1920's capstan lathes through to the (then) latest CNC's
Man has always been ingenious.
I would think that from pre WW2 to the advent of NC (C omputer came later) the technique for machining intricate shapes would would have been hydraulic copy - a stylus followed a 2D model of the desired shape and controlled a hydraulic ram (no lead screw). It was accurate enough to produce tolerances suitable for bearing fit. We still occasionally used hydraulic copy up to the time I left. It was 100% reliable, unlike CNC.