One of my first experiments with analog photography was to try out lightpainting, which basically involves long-term exposure of your subject in a dark environment and painting patterns and illuminating it with LEDs, light bulbs, torches or other light sources.
For the pictures shown here, I used my Olympus OM-4Ti camera with slide film on a tripod and simply drew some patterns and lines with blue and green LEDs near my guitar. This is already sufficient to obtain the basic shape and some beautiful reflections. The camera was set to bulb mode and the whole exposure took around 30 sec.