While this technically isn’t handmade, I stumbled upon it and liked the idea. Its the Eco button, and it reminds you to power down your computer to save energy and some greenbacks.
Its a USB plug in device that you just tap (like those funny/ irritating office supply button :that was easy:) when you’re stepping away from your desk to put the computer into power saving mode. See how much you’re saving too! check out the Eco Button