The Gemma will be placed in the middle of the bandolier, with one of the LED strips on either side.  We're wiring both strips’ data pins to the same Gemma pin (D1). 

This will make both strips show the exact same animations at the same time.  We'll get a symmetrical effect, with the animations running outwards in both directions from the Gemma.  

A Note about Power

This project assumes you'll have around 20-30 NeoPixels on each strip -- no more than 50-60 total in the project.  With just a few pixels we can keep our wiring really simple and draw power through the battery port on the Gemma.

If you plan to drive a lot more pixels -- say, if you want to use the stunning 144/m NeoPixels -- it's best to draw power directly from the battery instead of going through the Gemma.  

Here's a tutorial that shows how to wire up lots of pixels, connecting them directly to the power source.

Learn lots more about ways to power NeoPixels here.

Batteries

My favorite batteries for wearable projects are LiPoly batteries.  They're small and light, and will run a moderate number of NeoPixels for hours.  They come in various sizes so you can choose the right one to suit your project. 

However, “with great power comes great responsibility.”  If LiPoly batteries are punctured or mistreated, they could start a fire.  The wires also love to come disconnected from their solder points at the top of the battery, usually as soon as you get to your cosplay event or costume party.   

I always wrap a rubber band around the battery and wires to provide strain relief, and minimize the chance that the wires will pull out. A dab of E6000 glue at the wire-to-battery junction is another option.

And don't forget to get a charger!

If LiPoly batteries sound too troublesome, you can also power your project with AA or AAA alkaline cells.  This battery case will provide the right voltage, and has a nice on/off switch to boot.  Using AAA batteries means you can always find fresh batteries if yours have run out, and they're safer to use for kids, or for extreme cosplay events.