Just added a "Metallica Master of Puppets Gravestone"
http://www.shapeways.com/model/1537633/metallica-pinball-master-of-puppets-gravestone.html?li=search-results&materialId=6which you could try mounting near the drops on top of the plastics or at the back near the top in lanes or be creative to place them elsewhere
you can purchase directly from Shapeways USA.
flat white - $9.95
gloss white - $10.95
or I can print for $10.75 though will be slightly pitted white, not glossy.
It measures 40mm wide x 52mm high x 12mm deep and is hollow at the back to reduce the weight and manufacturing cost but you could also try to add lighting in there as well.
It has been print tested and has come up well, waiting for the camera to charge to take a photo.
