Make yourself a Steven Universe costume that will light up the world. This guide will show you how to make your own extra-sparkly handmade star T-shirt and Steven's gem. When you get all excited, the gem will light up and sparkle! It attaches to your body under the shirt, so you can flash your sparkly gem at bystanders and get them excited too.

If you're evil and you're on the rise
You can count on the four of us taking you down
Cause we're good and evil never beats us
We'll win the fight and then go out for pizzas
We are the Crystal Gems
We'll always save the day
And if you think we can't
We'll always find a way
That's why the people of this world believe in
Garnet, Amethyst, and Pearl and Steven!


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Other Materials Needed

  • A red t-shirt -- less stretchy is better than more stretchy
  • Sparkly gold iron-on transfer vinyl
  • A gatorade bottle
  • A hot glue gun with lots of sticks
  • An "ace" or other brand athletic bandage, the wider the better
  • 99% alcohol and a cotton swab

Ready to do this?

MakeCode is Microsoft's drag-and-drop code editor. It makes it easy for beginners and kids to get up and running with the Adafruit Circuit Playground Express. So many options are accessible and easy with MakeCode and it's really fun to customize and play around with making blinky lights and sounds.

Here's the completed project. Click the Download link at the bottom, plug your Circuit Playground Express into your computer via USB cable and drag the UF2 file onto the resulting CPLAYBOOT flash drive. 

Or, follow along below to create your own project from scratch.

Code It Yourself

Head to and choose the Circuit Playground Express. Select "New Project" and give it a name. I called mine "Steven's Gem."

Click the INPUT tab and find the on loud sound block. Drag it out into your workspace. Anything inside this block will happen whenever the Circuit Playground Express's onboard microphone hears a loud sound.

Click the LIGHT tab and look for the ring of lights. Drag this into your workspace and place it inside the on loud sound block you just made. Steven's gem is red, so I left mine red.  But you can make yours whatever color you want.

Then, back in the LIGHT tab, drag an instance of set animation for 500ms below the ring. Select the sparkle animation from the dropdown. This will add some white twinkly sparkles to your gem.

Check out the Circuit Playground emulator on the left. Click the sound icon to simulate making a sound. The gem lights up in red and sparkles! But.. it's over so quickly. Let's make it last a little longer.

From the LOOPS tab drag an instance of repeat 4 times into the on loud sound loop at the top. The two blocks from the LIGHT tab should pop inside it. Change the number in the repeat loop to go for as long as you want. I made mine 20 so it goes and goes and goes.

Finally, let's tell the lights to go off after the animations are done. That way you can surprise more people with your awesome belly button gem. From the LIGHT tab, drag a set all leds to red block into your workspace. Put it inside the on loud sound loop at the bottom, making sure it's outside the repeat loop. If it's inside, it will make the lights turn black (off) 20 times instead of staying black after 20 times.

Plug your Circuit Playground Express into your computer using a USB cable. You will see a rainbow animation appear the first time it boots up. Click the tiny Reset button in the middle of the board and the lights will all turn red, then green. When the lights turn green, a new drive will appear on your computer called CPLAYBOOT.

Note: If you get a drive named CIRCUITPY, no worries, press the reset button again (a total of two times) and you should get the CPLAYBOOT drive.

In MakeCode, click the Download button to download your code to a file. Drag this file onto the CPLAYBOOT drive. The Circuit Playground Express will reboot and eject itself. 

Clap your hands or shout to test it. Does the gem light up when you get excited? It does!

You can go back and change the colors to anything you want. You can also change the trigger - try making it trigger when you shake the Circuit Playground, or when you press one of the buttons. Try adding sounds too. Once you're happy with how it works, let's make the outside of the gem.


If you're having trouble, head over to the Circuit Playground Express tutorial for some troubleshooting ideas.

Make the Shirt

Start with a red cotton t-shirt that fits you fairly loosely. Steven Universe's t-shirt is pretty tight, probably from eating too many Cookie Cats, but the iron-on vinyl doesn't stretch much, so a very stretchy t-shirt might warp. Besides, you want to make it easy for people to see your gem.

Download the star template above at 100% size and print it out. Cut the star out, then lay it on the back side of your sparkly gold vinyl t-shirt transfer. Trace it with a sharpie, then cut on the line you made.

Flip the star over so it's face up. There should be a clear plastic covering on this side, which will keep your iron from melting to the transfer paper. Iron it on to the front of your shirt, following the manufacturer's directions. Let it cool completely, then peel the clear plastic cover off.

Gem Diffuser

We'll use hot glue to make the gem diffuser. The outside bottom of a 20 oz bottle of Gatorade is exactly the right size and shape. But feel free to do as I did, and go to your local drug store and check the bottom of every kind of soda bottle you can find against your Circuit Playground Express, until you find one you like. The stock lady may give you the stink-eye, but you are making ART, so it's definitely okay to do this.

While you're there, pick up a bottle of 99% alcohol and a stretchy, self-stick "ace" style bandage from the first aid supplies, and some cotton swabs if you don't have any.

Plug in your glue gun and make sure it's really hot and that you have extra glue sticks at hand. Then, fill the outside bottom of the bottle with 99% alcohol and swish it around a bit. Dump it out in the sink.

Take your hot glue gun and fill the indentation on the bottom of the bottle with glue. Do this quickly, before the alcohol dries and evaporates. It'll sizzle a bit, but don't worry about that. There may also be bubbles that appear, but they'll usually pop as the glue dries.


Once the glue is perfectly dry and hard, run a cotton swab with 99% alcohol around the edges to loosen the glue. Then, carefully peel the glue layer away from the bottle.

99% alcohol is like hot glue's nemesis. Hot glue can be un-stuck from just about anything using 99% alcohol. We have used it as a mold-release agent in this case.

This is a very useful trick! Put it in your bag of tricks and take it out often to show it off. 

Trim around the outside of your gem with scissors until it's nice and round. Then test it out by setting it on top of your Circuit Playground Express and making some noise! 

Wearing your Gem

Here comes the tricky part! How do you keep the gem and Circuit Playground and battery all nicely attached to your belly button? This is where our Ace bandage comes in.

Take your bandage and wrap it around your waist as many times as it will go, or 3 times, whichever is less. Make it snug but not too tight. Steven is chubby, after all -- we're not going for the Spanx look here.

Tuck your battery pack inside at the back, and run the extension cable around your side. Tuck the Circuit Playground into the front, right over your belly button. Place it behind just one layer of fabric so it's not too diffused and so there's a layer between your skin and the back of the Circuit Playground. Then, glue the hot-glue gem diffuser onto the top layer of the bandage with your hot glue gun.

Wear your shirt with pride, and whenever someone stops you for a Steven Universe-related high five, give a shout and flash your gem. The bandage disappears against your skin, if you were able to find a good color match, and the gem appears to be floating and twinkling right inside your belly button.

This guide was first published on Apr 02, 2019. It was last updated on Apr 02, 2019.