I've often enjoyed recreating artwork for modeling projects, but the licensing aspect on pinballs discourages me. But otherwise yes, decals are a relatively easy thing to do, especially for artists more skilled and proficient than me.
OTOH it's interesting that unique parts like ramps, etc, if not purely "artistic", still aren't considered copyrighted aspects of a given game's overall IP. 
(I do NOT mean to induce grief for FreePlay40 with that statement, but merely reflect on the apparent loopholes in IP/copyright enforcement).
Red Oak, TX
