Bending over her 80-year-old, cast iron loom, 27-year-old weaver Miriam Hamilton begins the clickety-clackety process of turning wool yarn into tweed. She’s carrying on a centuries-long tradition in her loch-side workshop on the Isle of Lewis in the Outer Hebrides, a chain of islands off the west coast of Scotland. Still, the ombre, nubby-textured fabric Hamilton makes will be turned into brightly colored men’s vests or used to cover chic lampshades, not old-school hunting jackets or Sherlock Holmes caps. “I want my tweed to mimic the patterns in nature,” says Hamilton, who works out of The Weaving Shed in the town of Crossbost. She learned to weave from a 90-year-old…