In article ,
Mike B someone@noplace wrote:

Presumably this was possible in the days before CNC machinery, so how did
they
do it?

For how, I think metalspinning is the likely best bet. At some point
(mostly the mold-making with metalspinning) there's some tedious "match
the parbola template" work, though mechanical options arise if an
ellipse (or a portion of an ellipse) will do just as well for an
application. A pattern-following lathe is another approach.

I know at least one guy (not me) who could probably get good enough
results with a sandbag and a rack of hammers (and a template to match.)

In any case there's going to be buffing involved for the finish.

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