Today I gave OSL (object source lightning) my first try. I airbrushed four tones of consecutive lighter shades of metallic tones onto the balls, using a steeper angle of the airbrush the lighter the colour got.

I think it is not to bad for a first try, but anyone who is able to produce OSL effects will probably laugh...

After the airbrushing, I painted the crevices black, then a thin line of white into the middle. Finally, I used a yellow green, a blue and a purple wash to imitate glowing. Unfortunately, on the photos the washes are not very visible... Using your eyes the effect is much more visible.