Make a gorgeous light up necklace using Circuit Playground Express and a real polished seashell.   The onboard push button makes it easy to choose between color palettes, to quickly match your outfit or your mood.  

There's also a button for brightness control: Turn it up to light up your sarong style at an afternoon beach barbecue, or turn it down to set off your evening gown in a romantic restaurant.

We've even included a sound reactive mode using Circuit Playground's onboard microphone.  When you talk or sing, your necklace will glow along with your voice just like Ariel the Little Mermaid.

A polished seashell makes the perfect diffusion material, but this build will work with a huge variety of materials.

This is a great beginner project with just a little (optional) soldering.  This project is perfect for kids, teenagers who need prom accessories, or for those of us who simply refuse to grow up.

If you're just getting started, get Lady Ada's Electronics Toolkit!  

If you just need a soldering iron, try this one.


1 x Circuit Playground
Circuit Playground Express
1 x On/Off Switch
SPDT Slide Switch
1 x Battery Cable
JST Extension Cable
1 x Battery
LiPoly 500 mAh Battery
1 x Battery Charger
USB LiPoly Battery Charger

Additional Parts

  • 3d Printed Circuit Playground case
  • Seashell or other diffusion material
  • Jewelry wire
  • Necklace cord

This guide was first published on May 31, 2017. It was last updated on Mar 08, 2024.

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

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