Here's how we'll wire the NeoPixels, 10mm eye LEDs, and speaker. Power will be provided by a power supply plugged into the HalloWing's USB port.
LED Eye Holders
Mark two spots on the eye sockets for the LED eyes to go.
Puncture the holes and then widen them with a tapered tool, such as a screwdriver handle until they're just wide enough to press fit the LED holders.
Wire the LEDs
Wire the LEDs by pushing their legs into the ends of the wire jumpers as shown. The long, anode legs of the LEDs go to positive (D13) and the short, cathode legs to ground (G) so keep track of the wire colors you use!
Push the LEDs into their holders. Note: the holders may pop out from the sockets as the LEDs go in, then you can push the holders back in place.
Next, plug in the jumper wires as shown, with the anode leg wires in D13 and the ground leg wires into G for ground.
Now, you can plug the NeoPixel strip into the NeoPixel port on the HalloWing, then loop the strip into the skull. Face the pixels inward to avoid seeing too many individual light sources.
Finally, plug in the speaker and USB micro/B cable for programming and tuck the electronics into the skull. Next we'll be programming the HalloWing.