I once used a phone flashlight to paint light in a long-exposure photo of an object, to get the specular highlights right (because I didn't have access to decen

I once used a phone flashlight to paint light in a long-exposure photo of an object, to get the specular highlights right (because I didn't have access to decent lighting otherwise). Basically I wiggled the phone around in the areas where I wanted lights to be, while another camera took a 15sec exposure.