Lucas Berbesson created this nifty homemade PixelStick, and he was kind enough to share the instructions, too.
The pixelstick is an ADRESSABLE RGB LED STRIP controlled by an Arduino that can display all sorts of animations to make awesome lightpaintings photographs.
Each LED acts like a pixel on a screen, displaying an image one vertical line at a time as you walk. These vertical lines, when captured by a long exposure photography, combine to recreate your image in mid air, leaving the person using it invisible. This technique is also called lightpaintings.
• DIY Pixelstick with image processing (YouTube / La Fabrique DIY)