Buzz when printing is done - Anet A8

Would you like your Anet A8 printer to alert you when your model has been printed?

I always wanted to know when my Anet A8 was done printing a model. Due to the fact that I am still on stock firmware, i.e. I can't run any script, I had to be more creative. So, I thought of a way to make the printer buzz when it’s done.

Parts needed:
1. A toggle switch
2. A piezo buzzer
3. An on/off switch
4. A piece of cable
4. A M3 screw with 2 nuts

Now, the logic is simple: Every time the printer