Synthetic spider silk that could be stronger than Kevlar and softer than any other material now available has been the holy grail for apparel companies, but it’s been tough to develop. Startup Bolt Threads, which has raised more than $200 million from Formation 8, Founders Fund and other, cracked the problem with engineered fiber based on the proteins in spider silk. Cofounder and CEO Dan Widmaier, who has a PhD in synthetic biology from University of California, started working on the problem during graduate school, and at one point had an office full of spiders spinning webs on hula hoops. Today, Bolt Threads has produced its first items of clothing – pricey neckties ($314) and hats ($198) – and inked partnerships with Patagonia and Stella McCartney, and it recently launched a second bio-material, a synthetic leather made from mushroom roots. Whether it can scale up the technology to make its threads (and leathers) at a viable price for anything other than the luxury market remains to be seen.