Static grass is something commonly found in various hobby applications such as model train boards, diorama building, and terrain and bases for miniature tabletop gaming. It is a synthetic fiber, colored to look like grasses, that is glued to a surface and then made to stand on end with the aid of static electricity. Commercial static grass applicators are available, and aren’t really all that expensive, but it’s a tool that is rarely used and it’s just cheaper and more fun to make your own.
Make: contributor Andrew Lewis spotted this well-documented build of an applicator on Hackaday and shared it with me. Even if you have no need for this device, the video is very well done and worth a watch if you’re interested in homemade specialty tool builds of any kind. The creator, Luke Towan, has a bunch of equally awesome how-to videos on making trees, rivers and streams, polystyrene buildings, and all sorts of components for terrain boards and dioramas.