Tap Mounting Holes
Before securing the HUZZAH board to the case, it's a good idea to tap the holes. Use a #4-40 machine screw to do this. Start by placing the screw over the mounting hole and slowly fasten it in - try your best to keep the screw straight so it doesn't go in at an angle. This will create threads. Do this for each hole.
Secure Adafruit HUZZAH
Place the HUZZAH board over the standoffs on the bottom case and fasten the screws. DO NOT fasten them all the way through - otherwise the screw will poke throught the case. You only need to fasten it a few turns, until the board is secured to the case.
Stick NeoPixel LED strips
Add pieces of double-sided tape to the back of each NeoPixel LED strips and stick it to the inside of the case. Reference the photo for best position.
Secure Case Halves
Insert 6 #4-40 3/8 flat Phillips machine screws into the back of the case and fasten them in until they poke through the top. Place the top half over the bottom half and hole them together while fastening the screws all the way in.