 Stretch nylon bikini briefs and bras complemented the adolescent boutique fashions of the 1960s , allowing those to be minimal . DuPont introduced lycra ( DuPont 's name for spandex ) in the same decade . Spandex expanded the range of novelty fabrics available to designers which meant suits could be made to fit like a second skin without heavy linings . " The advent of Lycra allowed more women to wear a bikini , " wrote Kelly Killoren Bensimon , a former model and author of The Bikini Book , " It didn 't sag , it didn 't bag , and it concealed and revealed . It wasn 't so much like lingerie anymore . " Increased reliance on stretch fabric led to simplified construction . It allowed designers to create the string bikini , and allowed Rudi Gernreich to create the topless monokini . Alternative swimwear fabrics such as velvet , leather , and crocheted squares surfaced in the early ' 70s . 
