Quoted from vec-tor:Maybe get someone to do a 3D plastic print of the eyes in a tall stack
formation and have an L.E.D. light it up.
Then, all you have to do is cut the eyes out... ;very tedious work.
Finally, push the new inserts from the top/bottom of the playfield till flush with the top of said playfield.
Might have to be a round nickle size base plate with two tall eye shaped towers.
I first would experiment on design and figure out what works best and what causes the least
damage to the playfield.
Their is available hobby plywood you can use to experiment on.
This is what I would suggest as well. There are plenty of translucent filament colors. Compared to routing out the PF, the 3d printed inserts should be cake to make