Bikinis have been made out of just about every material known. The fabrics and other materials used to make string bikinis are an essential element of their style and crucial modifiers of swimsuit design. The use of cotton made the swimsuit more practical, and the increased reliance on stretch fabric after 1960 simplified construction; alternative swimwear fabrics such as velvet, leather, and crocheted squares surfaced in the early 1970s. 

 

Fashion adviser Malia Mills has two basic criteria to check the material—it doesn't wrinkle into a bundle at the back, and nothing "falls out" when picking a towel or raising the arms.[66] Italian sportswear designer Emilio Pucci produced bikinis in soft silk jersey in his signature style. Norma Kamali's innovative designs utilized gold Lurex for a shiny sexy swimsuit.

 

Crochet, lace, PVC, raffia, fur, latex, velvet and other uncommon items are also used as string bikinis material. Speedo introduced Fastskin in 2007 as the lightest and fastest material for competitive swimwear. Unlike lycra, it does not break down in chlorine.

 

For the female bodybuilder the material regulations are more stringent, as "the two pieces of the bikini are fastened together with two strings, and the fasteners as all as the bikini must not consist of metallic material or padding. By 2010s, a number of manufacturers came up with environmental friendly bikinis that used organic cotton, organic bamboo fibers, fabric remnants, recycled nylon and eco-friendly dyes.