MIT media lab student Jack Forman used the under extrusion of a 3D printer to print a flexible textile material. Under-extrusion is when not enough plastic is consistently poured from the nozzle of a 3D printer, resulting in gaps in the printed material. By purposefully introducing these gaps, the printed material is solid and flexible. Check out the demo video which shows rolls of material being printed as well as applications like clothing and shuttlecocks.
