Light Painting Photography is the Art Form of using handheld lights to paint and/or draw in a scene while the shutter of a camera is left open during a long exposure photograph. I usually use 20 to 30 sec of exposure time with the camera on a tripod. Ideally the sky should not be too dark - a deep blue gives good results. I often use my DIY pixelstick with 144 RGB pixels driven by a Raspberry Pi.

Link to project-description of my DIY pixelstick (in German)