OK, perhaps I'm just 'NEW', but I had some slight wear on one of my PINS playfield, and could not figure anyway of correcting it.... until I found my new train of thought (outside the box).
Now I don't think you could apply this method for a large area, but minor areas should work - with either a clear coat overtop, or mylar protection..
I have used clear and white, and find white the best bet (but clear can be used for some cuctom work).
It's a neat idea with lots of custom oppertunities... so I thought I'd share.
If you already know about this product, great, please report your experiences...
http://www.decalpaper.com/http://www.testors.com/search?q=decal