I have 3d printed some plunger parts for my pinball machine. Best to use ABS, but whatever you use it needs to be very densely infilled, preferably 100%. These pieces are getting slammed really hard and, in this case, every coin going through the hopper rolls on the edge of the knife, it then has the pressure of the switch bearing down on the coin which transfers the load onto the edge of the blade. The original knives are made of that plastic like they make radiators out of, tough as you know what! Im sure it has a really long name that starts with poly!
If you do draft up the blade I would be interested in having the file. Its a complex curve.
Chris