In April, the startup Bolt Threads, which develops plant-based fibers like genetically engineered spider silk, debuted a new material called Mylo. Using mycelium, the surprisingly durable root structure of fungi such as mushrooms, Bolt created a leather-like material which, since it can be grown in a lab without involving large-scale animal agriculture, is much more sustainable than leather sourced the traditional way, from cows.

But with materials like these–and with innovative alternatives to other environmentally detrimental animal products, like the plant-based Impossible Burger or Modern Meadow’s Zoa, a liquid leather-like material grown from collagen–the real test of their impact comes in bringing them to market. Bolt Threads, in partnership with the Portland, Oregon-based company Chester Wallace, created the first-ever product made from Mylo, called the Driver bag, and will release it for pre-sale on September 5.

The starting price for one bag is $400, which Bainbridge acknowledges is fairly steep, but not too far off from what you might expect to pay for a good-quality leather bag. On Kickstarter, though, people can choose to pay $500 for a personalized embossed bag, or $1,000 to receive a smaller Mylo pouch and keychain along with the Driver. Chester Wallace designer Patrick Long created the two additional products out of the scraps left over from cutting sheets of Mylo for the Driver bags, so as not to waste any of the material.
As Bolt Threads begins to really scale up and streamline the production of Mylo, the cost for subsequent mycelium-based products will likely drop. Bainbridge says that both Stella McCartney and Patagonia have expressed interest in developing products with the “leather” (McCartney already crafted a sample Mylo bag, on display at the Victoria and Albert Museum, as part of the material’s release), and Bolt Threads is also in talks with a number of other companies to develop product partnerships. “The long-term plans for Mylo are much wider than just this one bag,” she says.