Fairy LED Bracelet

Contributors: Feldi
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In this project, we’ll create a wearable bracelet using Fairy LED String Lights and a rechargeable LiPo Battery cast in resin.

Design and build time: 30 minutes — 1 hour
Resin drying time: 24 hours

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Suggested Reading

If this is your first electronics project, we recommend reviewing the following tutorials.

How to Solder: Through-Hole Soldering

This tutorial covers everything you need to know about through-hole soldering.

What is a Circuit?

Every electrical project starts with a circuit. Don't know what a circuit is? We're here to help.

Battery Technologies

The basics behind the batteries used in portable electronic devices: LiPo, NiMH, coin cells, and alkaline.

How to Power a Project

A tutorial to help figure out the power requirements of your project.

Light-Emitting Diodes (LEDs)

Learn the basics about LEDs as well as some more advanced topics to help you calculate requirements for projects containing many LEDs.

Electric Power

An overview of electric power, the rate of energy transfer. We'll talk definition of power, watts, equations, and power ratings. 1.21 gigawatts of tutorial fun!


An introduction to polarity in electronic components. Discover what polarity is, which parts have it, and how to identify it.

How to Use a Multimeter

Learn the basics of using a multimeter to measure continuity, voltage, resistance and current.

Materials and Tools

The following shopping list includes the supplies from SparkFun that you'll need to follow along at home.

You Will Also Need:

Understanding the Circuit

This project is an example of a basic circuit – an electrical loop that travels from a power source along a path (called a trace) to a component (or components) that uses the electricity to function and then back to the power source. For our project, we’ll use an LED (Light-Emitting Diode). When this loop is completed by connecting the battery to the LED leads, electricity from the power source is able to flow from the positive (+) side of the battery through to the LED (lighting it up) and back to the negative (–) side of the battery. This electric flow is called current.

LEDs, like many electronic components have polarity, meaning electric current can only flow through them in one direction. That means that it matters which LED lead is connected to the positive ( + ) side of the battery and which is connected to the negative ( - ) side. If hooked up incorrectly, they will not light up. The batteries are also polarized; they have a positive and negative side. Always check the to make sure your LED leads are correctly oriented before soldering together a circuit. You can test this by simply trying one side and then the other or by using a multimeter.

Putting It Together


Start by sanding down the leads on the Fairy String LEDs. If you haven’t already, you will need to snip away any hardware that might have come with them to adapt to a wall or battery source.



Place the LiPo Battery in the Silicone Mold, followed by the string of lights. Make sure you keep the sanded LED leads and LiPo connector out of the mold.

inserting 1

inserting 2


Fill the mold up with as much glitter as it will hold. (This is optional. If you don’t like or want glitter, skip this step!)



Following the instructions on the packaging, pour the Epoxy mix into the mixing cup and use a paper clip to mix it together. Mix slowly as to avoid making air bubbles.



Pour the mixed Epoxy into the bracelet mold, setting all your electronic parts and glitter inside of the bracelet.



After 24 hours, remove the bracelet from the mold.



Find the + and - lead by using a multimeter or power source, and then solder on a JST connector accordingly.



Finally, insert your LiPo connection into the soldered JST connector, and enjoy the light!



Resources and Going Further

Want more e-crafting fun? Check out these similar projects for inspiration!

LilyPad Reed Switch Hookup Guide

A guide to using the LilyPad Reed Switch breakout in your projects.

Light-Up Plush

Craft a light-up plush with LilyPad LEDs controlled by pressing a button and sliding a switch in the creature's hands.

Illuminated Mask

Use LilyPad LEDs, a switched battery holder, and coin cell battery to make a fun light up mask for your next costume party.

LED PomPom Headbands

Follow this tutorial to make your own light up PomPom headband! Try the beginner version if you are new to electronics or the advanced version if you have some more experience!