Sometimes 3D printers mess up. They extrude too much material, or too little, or deposit material in the wrong spot. But what if this bug could be turned into a (fashionable) feature? Introducing DefeXtiles, a tulle-like textile that MIT Media Lab graduate student Jack Forman developed by controlling a common 3D printing defect — the under-extrusion of polymer filament. Forman used a standard, inexpensive 3D printer to produce sheets and complex 3D geometries with a woven-like structure based on the “glob-stretch” pattern produced by under-extrusion. Forman has printed these flexible…