While taking a photo, you can use light to create interesting patterns and drawings.
Equipment required for this includes a camera, tripod and flashlight.
After setting your camera up on a tripod in a dark space, you must set your camera's shutter speed to a very long one, perhaps 10 seconds. Then, set your ISO and aperture as low as they can go. You may also wish to set a timer for your camera. As the camera slowly takes the shot, draw patterns or shapes with your flashlight until it completes capturing. You will end up with intriguingly fascinating results. You can be more advanced and experiment by using different coloured lights or multiple lights.
This works as the entire time the photo is being captured, everything that the camera is exposed to, including the flashlight, is being tracked and is all merged into one photo, resulting in the patterns you drew showing up in the shot.
Photos from https://patrykhdesigna.wordpress.com/2012/10/19/slow-shutter-speed/ https://www.picturecorrect.com/tips/light-painting-how-to/