The Prop-Maker FeatherWing stacks on top of the Feather M4 express using the included headers. More about Feather and FeatherWing assembly can be found in the How to Solder Headers guide.
The GoPro case is just barely big enough to fit all our components, so we'll stack the FeatherWing directly on top of the Feather to make as small a package as possible.
The NeoPixel strip plugs into the port on the Prop-Maker Wing. We'll connect power and ground to both ends of the strip for a balanced distribution of power, and connect the data wire to the data IN end of the NeoPixel strip. Watch the arrows printed on the strip to be sure you're connecting to the correct end.
We'll use the G and EN pins on the FeatherWing for our on/off switch, and hook our momentary mode-change button up to G and A1.