When the Nike shoe company asked runners what they wanted from a shoe, the athletes “would describe all the characteristics a sock would offer,” says Nike designer Ben Shaffer. So last year the company knit them a shoe, the Flyknit Racer, which is now in the Cooper-Hewitt, National Design Museum in New York City. Cooper-Hewitt textiles curator Matilda McQuaid calls it an “innovative use of knitting”: The company had to develop a polyester yarn of varying elasticity, thickness and strength, plus machines to weave it into a virtually seamless mesh upper that expands and contracts with the wearer’s foot. The manufacturing process minimizes waste, and the result is a shoe that fits like a sock, supports the foot and weighs just 5.6 ounces. After the Flyknit hit the market (at $150 per pair), Adidas began selling a similar model called the adizero Primeknit. The two companies soon got into a patent dispute.