Hi George,
Perhaps give a try the same sort of techniques telescope lens and mirror makers use. Maybe cast a plaster of paris depression in the shape of the condenser, line it with felt or some suitable cloth and then put a bit of polish or paste at the bottom where the dings are and move the condenser around.
I'd probably just do it by hand, and put a bit of paste on a cloth and put that part of the cloth in the palm of my hand near the base of my thumb and polish.
Making a mold could work if one especially wanted to retain the identical (spherical?) shape of the condenser by polishing the whole surface down the same number of micrometers. I don't know how important that might be, but I'd guess it's not too important or necessary.