So you want to make your own colorful Cortana costume? Adafruit has published a guide that shows you how to do just that. You are going to need a Gemma, NeoPixels, NeoPixel Rings, a battery, conductive thread, and a few other parts to get started. It is a nice project for those of you who are serious about building your own wearables.
The above video provides more information about this project. More information is available here.