+Adafruit Neopixel Tiara on an Actual Tiara- Almost Built

Design change:  I have ruled out the CR1220's (not enough battery life, too hard to change), and the CR2032's (too bulky). +Becky Stern  was trying to push me towards a LiPo battery, and I resisted...but finally realized she is right. The 100mAh version is small and the right size to fit the tiara.

I sewed eacghneopixel to the tiara using silver
thread.  Here's the first, ready to go..
The "V2" on the back side happens to be on the
"data-in" pin, so I started there with each one.

Here's the tiara with pixels shown. I'm still have to clean up the stray threads.

The sewing took me an afternoon (not an expert), but I got it done and it's not too ugly.

Next I soldered the neopixels together (+ to +, - to -, DO to DI), then connected the Gemma to the first neopixel for a test, using alligator test leads--see the video. The soldering took a couple of hours. For each wire, I used calipers to measure the distance between neopixel pads, stripped 14", marked the desired length of unstripped wire (from the calipers), cut the wire 1/4" beyond, and stripped 1/4" off that end.

I did the data bus first, and used stranded wire.  That turned out to be a huge pain--it's too flexible and the ends are hard to deal with.  I switched to 22awg solid core wire for the power and GND busses. Much easier.  I will go back to stranded when I wire the Gemma, because I will need the flexibility.

Also, I discovered (or remembered, not sure which) that Gemma has an on-off switch on board.  That simplifies this circuit (I don't need to add a switch).

Next:

• trim stray threads and wire to clean up as much as possible
• re-sew at least one of the neopixels (some threads got burned during soldering)
• secure and insulate the threads and wires with nail polish
• add the 100mAh battery
• glue the Gemma to the tiara
• solder the Gemma connections to the circuit, attach the battery to the tiara.

Parts list:

• 100mAh LiPo battery
• 26AWG Silicone-coated stranded wire
• 22AWG solid-core hookup wire
• Flora RGB V2 Neopixels (6)
• Plastic Tiara (found a pack of 6 at Party City, which is 50mi away--ordered online)
• Gemma (could also use a Trinket...)
• Needle and thread
• Nail polish 
• Soldering Iron and associated paraphernalia
• A battery charger like this would be helpful