I read this out to my girlfriend (as well as a few other responses of yours in this thread) and had to ask for clarification on a lot of the terminology (roots, tack, gore - ha, neat!). She designs and sews all of their products herself, and helps some women with fitting but she isn't a bra fitter. We both found your comments very interesting. Thank you!

So a physics simulation would need to include the shape and density distribution of the breasts. Hypothetically, it would then be able to simulate dozens of bras with reference sizes and how this would look (i.e. an image output). At this point an expert system trained on images of good vs bad fit could probably visually recognize common problems and return a few of the best bras. This is probably oversimplifying, and it's already too complicated to actually be done, so I think it's not the right approach.

Do you see any aspect of bra fitting which _would_ benefit from technology? i.e. some kind of specialized fitting tool