You can do an awful lot with a cutting torch and a 2x72" belt grinder.
Back in the day they used cutting torches on magnetic tracer machines. You just made a sheet metal template and a knurled magnetic stylus rolls around the outside (or inside) at the right speed for the cutting tip you are using on the thickness of steel you are cutting. Those parts don't even really need to be finish machined most of the time if you're making something like a hand crank lever. Nowadays laser and waterjet have replaced the mag tracer pattern cutters. My advice is to find a guy with a waterjet machine and make friends with him. A waterjet is basically a very high pressure wet sandblasting nozzle that moves in a 2D path CNC.
You can in a pinch get a bunch of identical parts lasered out, stack them up and weld them together to make a very thick part.
About how to imitate a CNC machine job by hand I have nothing useful to add.
metalmagpie
I'm thinking it was 45 years ago when the fabrication shop my father managed purchased a pattern cutter that used a torch to cut heavy plate to a pattern. The patterns were drawn at 1:1 on drafting paper. They had to be sharp and black, so we had to break out the ruling pens and draw 1/8" lines in ink.
Of course, the part was only as accurate as 1.) the drafter and 2.) torch cutting, neither of which can work to typical machining precision. (I could draft to .010 but the machine followed 0.125 lines.)
That was early stuff, of course.
I have wanted in the past to make accurate cam plates for automatic focusing devices on cameras and enlargers, and these are often complicated mathematical shapes depending on the other geometry of the machine. The best I could do was using a band saw and a drum sander, both of which limited me to aluminum (which was fine in those applications). But it was tedious hand-fitting, never attaining the sort of accuracy really needed, and only providing a starting point for final manual focusing.
The timekeeping industry and the cam slots in things like zoom lenses used to be made to tenths or even millionths precision on production machines long before CNC. But the effort went into making the patterns the production machines would follow. Those jobs were all about metrology and skill. CNC has made that much easier. People think the wristwatch mechanical movement industry is mired in the past, but though the movements are an archaic technology, the machines that make them continually push the boundaries of the state of the art.
Rick "reading the responses with curiosity" Denney