A while back, MIT researchers found a way to easily create 3D-printed hair: smart software can create thousands of tiny polymer strands (smaller than 100 microns, if you want) that give objects a fuzzy texture. Now, however, they're finding practical uses for those natural-feeling surfaces. If you specify the right angles, density, height and thickness, you can make the hair do surprising things. On a basic level, you can create blocks that only stick to each other under certain conditions, or paint brushes that produce very specific effects. However, it really gets interesting when you vibrate the hairs -- you can create motors and sensors that are as baffling as they are clever.