Using Matthijs Kooijman's blog post, we are going to use the built-in (since Raspbian sketch 2017.08.16) power button code using PIN 5 and a ground.

Parts list:
Momentary Power Button (https://www.amazon.com/gp/product/B00...)

Connector Wires (https://www.amazon.com/HiLetgo-5x40pc...)

Matthijs Kooijman's blog post:
https://www.stderr.nl/Blog/Hardware/R...