Still experimenting with this technique in order to get ready for a workshop tomorrow.
Obviously, if you're painting with *light*, the light source is pretty important (nothing like understating things). The difficulty thus far is controlling the spread of a conventional bulb light when using small subjects like this 12 inch long truck. I just order an inexpensive 20" long fiber optic adapter that will attach to the end of a Mag light to see how this might allow more precise light placement. Too late for the workshop, but....
This technique certainly allows for more dramatic lighting that just hitting the subject with a standard flash. I've found that a few editing steps with Nik's Color Efex Pro helps produce a more evenly lit and pleasing result.