I was a professional airbrush artist for quite a number of years before I switched to painting in oils on canvas. I studied the same techniques as Dru uses and for an airbrush artist who is proficient and using quality equipment it's not hard to produce work like that. Airbrushers use many techniques to produce the overall photorealistic effect. It's not at all hard, you just need the patience. After a number of years painting photorealism I got bored of it, I just never felt I was creating anything worthwhile, you soon get fed up of people saying "it looks just like a photograph". I gave it up photorealism overnight and came up with my own unique style and now painting is a joy everyday of the week.