Bra rub off can sound dirty, it’s when you make a sewing pattern off an already constructed piece of clothing. I haven’t tried to do this with currently wearable bras, but I hear it is totally doable. This is about is about when good underwires go bad. As a skilled seamstress I know working on a pattern could take anywhere from three to five makes to get the fit right. With a RTW one that already fit well I knew that number could be reduced.