Ergonomics teaches that the “average man” doesńt exist. Panero and Zelnik [1] say that make three measures coincide in the same person is a small chance: 3%. A guided observation in a swimming pool makes it easy to realize this fact: if a woman that is L (large) on the bust buys a swimsuit, she must be also L in the whole body, or the garment will have a bad fitting in any part that's not L. This paper discusses that not every women have the whole body in a same standard size “small”, “medium” or “large” and the objectives that guided the research were realize what options of swimsuit exist and how could modeling satisfy that ergonomics issue. Buying a swimsuit, for those who are not small on hips and small at the bust, is always a choice of bad fitting. The situation gets even worst if she is not in the “average” height. Normally women choose to buy the size that fits their biggest measure, and at the part of the body where fabric was not needed in that amount it over abounds. Guided observations in a thermal center and interviews in a public swimming pool with structured enquiries were made for this research which purpose was verify what do industry offers to ladies above fifty years old as swimsuits for indoor activities, what kind of situations of discomfort they experiment and what they would change in it, if it was possible. The main results of this research are that swimsuits, for ladies above 50 years old, must have a sewing line under the bust, allowing better accommodation of breast; problems with the straps, that commonly enlarge with some use; and the size, that doesńt fit comfortably if the shape of the user is not the same size at the top and at the bottom. This paper presents the alternative of inviting customers who doesn’t have their needs fulfilled by the common stores (“non average woman”) to choose each part of a modular system of swimwear as a good way to apply the studies of design project, converting swimsuits “three size fits all” into swimsuits that really fit.