Place the PropMaker inside the plastic case. You will need to remove the wires from the screw terminal to get it in there, but this is a great opportunity to adjust the length of the wires so they just reach the board without a lot of extra loops.

Thread the female connector from the switch through the hole in the top of the case. Plug it into into the onboard JST connector.

Close up the case and use some hot glue to secure it to the very top of the headband. I used my heat gun to bend the side slots down just a bit so it forms to the top of the headband a little better, and added a little glue to the top of the case to keep it from popping off.

The head-tilt code works best if the board is placed directly on the top of the head, with the USB port facing forwards. 

Secure the on/off switch on one side of the case, and carefully glue the battery down to the other side. Your placement may vary, depending on how you're planning to mount the horns, but put the switch someplace accessible. Don't worry about the battery being accessible - the PropMaker has onboard charging capabilities, so you won't need to remove the battery for charging.

While you're charging, make sure the switch is open / turned on. The switch makes a physical break in the line from the battery, so the controller can't charge the battery if the switch is in the closed / off position.

Mount the horns on the headband with hot glue. I used a whole lot of glue, some on the inside edge and some on the outside, so they feel super secure. This paper mache mixture is flexible like leather and gives a really good surface hold with the hot glue.

Add flowers, grapes, skulls, or lace to hide the electronics. I used craft wire and hot glue to secure everything. I also sewed a couple of wig clips to the underside of the headband so they grab my hair, allowing me to toss my head with abandon on the dance floor without fear of losing my horns.