Quoted from Richthofen:
Those photoshop files are of incredible value. It would be nice to build a database of artwork files (cabinet stencils, playfields, plastics) and host it somewhere on the internet so people could get them printed themselves.
There used to be a web site called "balls of steel" that had scans of a lot of pinball artwork, mainly plastics if I remember correctly.
It was shut down due to copyright issues. I believe that it was Wayne's lawyers that caused the guy to get pissed off, so he took down the scans on the site. Though the scans conceivably still exist somewhere.
Perhaps someone from RGP can chime in with more info.