Similar methods are already in use in clothing design. Programs and patterns have the "extra space" built in; the jargon for it in knitwear is "ease" and it var

Similar methods are already in use in clothing design. Programs and patterns have the "extra space" built in; the jargon for it in knitwear is "ease" and it varies not only according to desired fit but also type of yarn/fiber. A garment with negative ease, for instance, needs to expand to fit onto your body, while a garment with positive ease is larger than the body measurements, and of course you could vary the ease within the garment. There is some interesting engineering that needs to happen near large joints -- as you say, a "perfectly form-fitting sweater" might have some difficulties at the armpits for instance as we have such a range of motion there. But these are well-studied problems!