Around Shenzhen, since mid-December a cottage industry of more than 1,000 factories that were churning out the boards has shrunk to a couple hundred. “We maybe lost 50% of our revenues after the Amazon announcement,” says Feng, speaking from his shamrock-green factory floor. ... Unlicensed manufacturers had begun copying Chic’s board immediately after it appeared at the Canton trade show. By the summer of 2015, more than a thousand factories—up to 10,000, by some estimates—were making boards for distributors who sold them abroad online. Factories like Feng’s that had been making LED screens or iPhone cases switched to building hoverboards in a matter of days. And many factories, licensed and otherwise, cut corners on safety standards, often by subbing in cheaper, potentially flammable batteries.