Colin's original design introduced a raspberry shutdown button at the side of the modular display, and a status LED at the bottom of LCD. I found a nice push button that has a built-in LED - I went for orange to match by theme, but they have a few other colors as well:
https://www.amazon.com/gp/product/B095S74R5C/
I have also added a rocker switch to the the side panel while I was at it.
The author remixed this model.