I’m sure most of us do our 3D prints unattended and after the print, it will just leave the 3D printer there eating away at your electricity. There are similar mods around using end stops trigger or a timer, solutions that ain't neat. I did some searching and found the perfect electro mechanical device that can simply turn off your printer with the M81 gcode command and also a soft switch to turn on the printer just like on the desktop computer. The printer is completely shutoff with no stray or standby current. Here's how the auto shutdown looks like at the end of the print: https://youtu.be/3tQqf38rrog