I don't know example project but I can give you some recommendations
You have to know how your coin acceptor works...
I recommend you the following product of Adafruit:
You also will need arduino with some Internet connection (wired or wireless).
Also relay board would be needed.
How KWats is the washing machine?
We can start to discuss some major things to help you with basic scheme and configuration.
Also this one could be some kind helpfull: