The eject shield is the piece of plastic that hold the ball in a ball trap. This is the red square part in the pic.
For the design of the ball eject assembly, I first drawn up the normal eject shield. This can then be used to as a base for my own one ball eject..
Here you can see the eject shield plastic from the top:
The problem as always that I don’t have access to one. So have to resort measuring some pictures and then hope you have the correct sizes. With these make the following design:
The ramp is different, because the two little points in the original design are really to fragile in a 3d printed part.
Interesting is that the ball is not centered in the hole, but is offset by about 2mm. This allows the ramp to extend to the top of the 12mm playfield.
Some other views
Viewed as printed part.