Simple Auto-off addon for any printer

Hi all. This is my first contribution to the Thingiverse comunity and I hope you find it interesting and useful.

Since my first prints the need of turning off my printer manually once the piece is finished always bothered me. After almost a year tinkering with my printer I finally decided to do something about that.

I know that the fast answer is Arduino, but it comes with some issues like "I have to find 9Vdc" or "I don't want to waste a board with such a simple task". The good thing about it is that it's the easiest way to add other features without messing around with more cables. However, since I'm not interested in expand any functionalities anytime near soon and my main working area is automation I decided to desing the auto-off only based on relays.

Also it was important to me to be as less intrusive with the printer as posible, as I am against making new holes or cutting any wires.

I think this is the easiest way to add this feature and I haven't seen it posted any