making custom LEDs - electrocuties

Learn how to make your own custom LEDs in cute shapes with cute decorations!

Many electronics tutorials involve LEDs (Light Emitting Diodes)—beginner electronics tutorials use them as a “Hello World”, and other electronics tutorials might use them to test that the rest of your circuit is working, or as a status light! LEDs are already cute—they come in various colors, they’re small, they light up—but if you’re going to be using them in a lot of projects you might as well make them custom and even cuter!

Designing your dream LEDs

What kind of LEDs you want to design might affect what kind of supplies you use, so let’s brainstorm before we get started! What shape do you want your LEDs to be? Stars? Hearts? Cat-shaped? What color do you want your LEDs to be? Pink? Purple? A constantly-changing rainbow? Do you want your LEDs to have any kind of decoration inside them? Glitter? Confetti? Flower petals? Sprinkles?

Supplies (Resin Version)

This tutorial can be done with either resin or hot glue. We’ll share the resin version first, but if you don’t have resin supplies or would rather not use it for safety reasons, you can find the hot glue instruction modifications further down!

standard LEDs in your color of choice: you can find these at electronic supply stores like adafruit.com. If LEDs aren’t available in the color you dreamed of in the brainstorming stage, you can get clear LEDs and achieve your dream color via resin dye.
UV resin: for this particular project, UV works well since we’re making small objects which should cure quickly under a UV light. Also, you’ll have to hold the LED in place as the resin cures, so you won’t want to use AB resin which cures in 24 hours.
UV resin light: I use the same kind as is used for curing gel nails.
Resin dye & toothpick/stirrer: if you want your custom LED to be a different color than the LED you’re starting with
Transparent silicone molds in the shapes you want your LEDs to be: I used heart and star shaped molds for my LEDs! There are a lot of shapes and styles available on Etsy or other craft stores. Make sure they’re transparent so the UV light can get through them to cure the resin.
Glitter, flower petals, or other decorations: you can put these in your LED for some extra customization!
3V coin cell battery (or other voltage, depending on what your LEDs need) and optionally alligator clips to test that the LED works, before and after you customize it
Tweezers to place resin decorations and to hold the LED in the resin as it cures
Safety mask: resin has toxic fumes so I recommend wearing a shop mask/N95 mask and opening a window when you work with it
Latex gloves: You don’t want to touch resin, so either wear gloves while working, or be careful to only interact with the resin via tweezers

One of my biggest resin inspirations is @fantasia_miran on Instagram. If you’re not sure about what shape or decorations to use for your LEDs, I’d recommend browsing for ideas!

1. Test LEDs

I always recommend testing your electronic components before you do anything to them. If your LED no longer works after you’ve modified it, but you never tested it to begin with, you won’t know if you did something to break it or if it just never worked to begin with.

Most LEDs need 3V of electricity to light up, but check your specific LEDs. LEDs also need a resistor to lower the current to their working specs, but for testing purposes, it’s ok to briefly connect the LED to a coin cell without a resistor. Coin cell batteries don’t produce enough power to burn out the LED. LEDs are directional, meaning it matters which end of the LED you connect to the positive end of the battery, and which you connect to the negative end of the battery. You’ll notice one of the LED “legs” or leads is longer than the other. Connect the long end of the LED to the positive side of the coin cell either directly by putting the coin cell between the LED leads or with an alligator clip.

connecting an LED to a 3V coin cell battery

2. Fill the resin mold with decorations

Prepare your workspace by lining it with paper or parchment paper. If resin cures on your work surface it might be difficult or impossible to clean it off. Next, pick a resin mold to use, and line it with whatever decorations you’d like to use.

Heart shaped resin mold filled with pink dried flowers

Star-shaped resin mold filled with holographic star glitter

3. Fill resin mold with resin

Next, while wearing a safety mask (and maybe gloves too), fill the resin mold with UV resin. If you want to suspend more of the decorations throughout the LED, alternate adding decorations and resin in layers. If you want to add color to the resin, you can do it in this step. Add a tiny drop of resin dye and stir with your toothpick.

4. Cure resin while suspending the LED in resin with tweezers

Next, you’ll want to put the LED into the resin, and cure the resin with the UV light. You’ll want to suspend the LED upside down in the resin with tweezers like this:

Use tweezers to hold LED in resin, via the LED leads. Continue holding this way while curing the resin under a UV light.

And keep this position as still as possible while placing the resin mold under the UV light. My UV resin light has a counter to 90; if yours doesn’t, set a timer to check the resin after 90 seconds.

After 90 seconds, you can check the hardness of the resin by poking it with a toothpick or by trying to wiggle the LED with the tweezers. It might need another round under the light if it’s not completely hard. But even if it’s not completely hard, it’s probably set enough that you don’t need to hold up the LED with tweezers.

5. Test your LED and admire

After the UV resin has set, it’s time to test it, via the same methods as step 1.

lit up heart LED with dried flowers (LED used was “warm white”)

lit up star LED with star glitter (LED used was rainbow)

[content warning: flashing lights]

video of the the rainbow star LED in action

video of the cured heart LED, not lit up

Hot Glue Version

If you don’t have resin supplies, or if you’re worried about the potential safety risks of resin, you can make a version with hot glue! The process is very similar, except :

You can use either opaque or transparent silicone molds.
After covering the surface of the mold with decorations, fill the mold with hot glue instead of resin.
Before the hot glue cools, place the LED in the hot glue and hold the LED in place until the glue hardens.
Though hot glue doesn’t have the same toxic fumes as resin, working with hot glue still requires care and caution since the hot glue and the tip of the hot glue gun can burn you.

Here’s what the hot glue version looks like!