Sometimes you want to add animated lights to your costume or project and you're really limited on space. Necklaces are a great example of this - a glowing pendant can be so striking, but if it's too big and bulky it can cross the line to "gaudy" pretty quickly. 

This tutorial aims to make the smallest possible NeoPixel module or insert for your project. We've worked to make it super small, at around 1/2" thick and about 2" across.

This tiny package still contains all the niceties:

  • 7-12 addressable NeoPixel lights
  • A compact on/off switch
  • A rechargeable battery with 4+ hours of battery life
  • Onboard USB charging capability

We're using an ItsyBitsy M0 microcontroller, and we've included an easy-to-customize code sample as well.


Electronics Build

The physical build is the tricky party with this project.

This is an intermediate project that requires some tight soldering and careful measuring and cutting. You'll need to work small, and working small can be a challenge. But it's all through-hole soldering -- nothing fancy -- so it's definitely doable with a good soldering iron and a little patience.


We've provided CircuitPython code for this project. The code is pretty straightforward and easy to customize with a few keystrokes.

Price Point

We've tried to keep this project fairly inexpensive so it's easy to fit into your cosplay budget. With a NeoPixel jewel, the cost of this project is around $25-$30 including everything you need.

Parts Needed

Angled shot of Adafruit ItsyBitsy M0 Express - for CircuitPython & Arduino IDE.
What's smaller than a Feather but larger than a Trinket? It's an Adafruit ItsyBitsy M0 Express! Small, powerful, with a rockin' ATSAMD21 Cortex M0...
In Stock
Adafruit LiIon/LiPoly Backpack soldered onto a Pro Trinket, plugged into a solderless breadboard.
If you have an ItsyBitsy or Pro Trinket you probably know it's the perfect little size for a portable project. This LiPoly backpack makes it really easy to do! Instead of wiring 2...
In Stock
Lithium Ion Polymer Battery 3.7v 100mAh with JST 2-PH connector
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This...
Out of Stock
Breadboard-friendly SPDT Slide Switch
These nice switches are perfect for use with breadboard and perfboard projects. They have 0.1" spacing and snap in nicely into a solderless breadboard. They're easy to switch...
In Stock

NeoPixel Choices

For my necklace, I'm using a NeoPixel Jewel with 7 pixels. This project would also work well with a 12 or 16 pixel NeoPixel ring if you want more lights.

And in case you're wanting to pack in as many lights as possible, here's a tip: the NeoPixel jewel fits perfectly inside the 16 pixel ring! So you can pack in 22 dense little lights within the 2 inch radius, if that's what your project calls for.

NeoPixel Jewel - 7 x 5050 RGB LED wired to Trinket, lit up rainbow
Be the belle of the ball with the NeoPixel Jewel!  We fit seven of our tiny 5050 (5mm x 5mm) smart RGB LEDs onto a beautiful, round PCB with mounting holes and a...
In Stock
Hand holding NeoPixel Ring with 12  x 5050 RGB LED, lit up rainbow
Round and round and round they go! 12 ultra bright smart LED NeoPixels are arranged in a circle with 1.5" (37mm) outer diameter. The rings are 'chainable' - connect the...
In Stock
Hand holding NeoPixel Ring with 16 x 5050 RGB LED, lit up rainbow
Round and round and round they go! 16 ultra bright smart LED NeoPixels are arranged in a circle with 1.75" (44.5mm) outer diameter. The rings are 'chainable' - connect the...
In Stock

This guide was first published on Sep 16, 2020. It was last updated on Jul 19, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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