I made my own wearable computer with a Raspberry Pi, and it was almost too easy

Ever since I read about the crazy wearable pioneers back in the ‘90s and early 2000s, I've wanted a wearable computer of my own. I had two major requirements, however: it had to be a computer, and I had to be able to wear it.
Smartphones, for the most part, have supplanted most people's interest in or need for a wearable computer. They're great, I highly endorse smartphones. But you can't really "wear" them in any functional way.
And then there was Google Glass, which was super usable, and