We had ours cut out of vinyl on a machine you hook to a computer...it's called a plotter.
Basically it takes a vector image file (like you'd make in Illustrator, etc etc) and plots all the points onto a material (we used vinyl...you can use a plotter with various things). This allowed us to make our "wings" last year look like this:
http://firstubergeeks.com/gallery/vi...d=team_pho to
I know it's not fancy, but we didn't have our own plotter (then).
Anyhow, if you have more questions I'd be willing to help you out, but I'm sure there are ways to get much cooler looking art onto your bot than this.