Me too, 5 years ago:
http://homebrewpinball.blogspot.com/2014/04/ben-heck-eliminate-bulbs.html

SO glad someone took the initiative to actually DO IT. Also very happy to see the light projects through regular glass. I never agreed with the way multimorphic decided to put a giant LCD screen in the middle of the playfield (but commend them on their PROC platform). This allows complete mechanical freedom without compromise. I really think this could change pinball drastically. Everyone complains "oh, there's only so much space on the playfield". well if you could change the art on the playfield, plastics, and targets this could allow a more video game experience where the entire playfield could change modes. I can only imagine what this could do for movie themes.

Great job guys, can't wait to see what you do with it!

One other thing (that I'm sure the OP of this thread has already realized but maybe others don't). With a system like this, theoretically you eliminate all insert and GI lighting. Not only does that dramatically reduce cost both in parts and labor (depending on what the projector costs) but it eliminates a ton of wire and spacer potentially opens up more room for under playfield mechs. Seriously, all that NEEDS to be underneath as far as wiring is for coils and switches.

It might get busy trying to project over existing art.. If you've ever seen them project map on top of a building it works ok, but it's also VERY dark. Any amount of light from something else would reveal the art

Not to simplify it, but there's not a lot of magic to it. You mount a projector rigidly in place, turn it on.. then in realtime with a paint program in full screen mode you trace the outside of the objects. Once you have that, you can paint whatever art you want in each section like a coloring book (obviously animating 3D objects is a lot more involved), but basic 2d art is pretty simple. This video shows a good example:

If you have a spare LCD projector laying around you can try it at home. I picked up a used one on ebay a few years back for $30.

bright projector. Laser projectors can only do vector art (which wouldn't be a bad thing, but could take longer to program and you'd get that flickering effect)