In medieval times, suits of armor, rather than three-piece suits, were all the rage for men. These weren't typically purchased off the rack, either; instead, armorers meticulously crafted them.
An armorer would begin by taking a customer's measurements, and then making a wooden mannequin or wooden body parts to use for the fittings. Since steel was exceptionally rare in the Middle Ages, an armorer would typically take, say, an old, battered helmet or a dented breastplate to forge into new pieces. Over time, armorers developed trade and military secrets, which they passed down from father to son, as this was often a family business [source: Olexa].
Interestingly, armorers were given a lot of time to create their suits — often years. What the customers did in the meantime is anyone's guess. Over time, suits of armor were deemed passé. They were too heavy for foot soldiers. By the 18th and 19th centuries, breastplates and back plates were generally the only pieces being used, and the invention of muskets that could pierce armor put an end to them. Today those pieces are made of materials such as Kevlar, not steel [sources: Medieval Warfare, Olexa].