Mega-stylist to the stars, Karla Welch is here to guest-mentor the designers and she's got a job for them – dress her client: the one and only Karlie Kloss! Karla's got a twist though, the materials used to design the look will be donated clothing from a local Goodwill, making this Project Runway's first upcycling challenge. The designers will need to be resourceful, sustainable, and fast because it's also their first one day challenge. One designer's dreams will come true with the chance to dress a supermodel while another will be all out of second chances in this second-hand challenge.