[pureliquidhw]

I'm guessing because there are more dimensions than simply shape of breast that affect the fit of a bra.

I wonder if a machine could be made that inflates/deflates a proxy of a bra until the woman (wearer? Am I assuming gender?) is comfortable. Take the readings of a comfortable fit and construct a bra that provides that support. Basically, you don't care about the shape of the breast, you care about the shape of that individual's comfortable breast and the pressure needed to get it into that state.