Every summer, the Stockholm-based, Scottish-born designer David Taylor retreats to his family's cottage in the Swedish countryside for a spell and spends his days foraging in the woods. It isn't greens and mushrooms he's after, though, but slag — the decidedly un-edible clumps of waste compounds left behind in the production of metal. Taylor's cottage happens to be in a town called Hälleförsnäs, also home to an iron foundry that was built in the 1600s and shut down for good in 2006. "Slag can still be found just about everywhere around here," Taylor says. "It’s a worthless by-product that was produced in huge quantities and mostly just dumped out of sight in the forest for centuries." For a recent project that debuted during the Saatchi Gallery's Collect fair in May, Taylor gathered up chunks of the stuff and upcycled them into a series of colorful candlesticks.