Blue Spirit Hairpin – Avatar: the Last Airbender Inspired LED Project

Bring the iconic Blue Spirit to life with this unique 3D-printed LED hairpin! Inspired by Avatar: The Last Airbender, this project combines simple electronics and 3D printing to create a wearable art piece that lights up. Whether you're a cosplay fan or just love cool DIY accessories, this project is for you!

1. Access to a 3D printer
2. Cura slicing software
3. 3V lithium coin cell batteries (x1)
4. 220 Ohm Resistors (x2)
5. White LED diodes (x2)
6. Electrical tape or copper tape
7. Acrylic paints & paintbrushes
8. Sandpaper or sanding tool
9. Mod Podge or varnish (optional for sealing)

Start by searching Thingiverse.com for a Blue Spirit mask model. I originally considered printing just the mask as a badge, but I found a model where the sword is used as a functional hairpin—perfect! The file was already split into two parts: the mask and the sword.

Import the STL files into Cura. I printed the first version at 34.1% scale, but found that the sword was too small—it disappeared into my hair when I tested it with a bun. The mask also didn’t hold much hair, which limited functionality.

So, I went back into Cura and rescaled both the mask and sword to 50% size, making sure the sword stayed proportionally sized in width to fit the mask.

The second version looked great and was much closer to my vision. However, the longer sword didn't quite fit into the slits of the newly scaled-up mask—it turns out I didn’t account for slight changes in thickness even though I kept the width the same. Since printing took over 26 hours, I decided to move forward with the first version and focus on the finish.

After removing the supports, I sanded the surfaces smooth and painted the model using acrylic paint. To avoid paint scratches during final assembly, I recommend sealing your pieces with Mod Podge or varnish once the paint is dry.

Now for the fun part—making the mask’s eyes glow! Originally, I taped a single white LED to a lithium battery, but it didn’t light up both eyes enough. So, I upgraded:

1. 1 lithium batteries
2. 2 white LED diodes
3. 2 220 Ohm resistors
4. Positioned each diode behind one eye
5. Secured the components with tape

This setup gave a bright, even glow that really brought the mask to life.

With the circuit in place and the sword painted, I slotted the sword through the back of the mask (first version). And just like that—the Blue Spirit came to life in hairpin form!

If you reprint, make sure to adjust for all sword dimensions, including thickness!

Use a sealant to prevent paint from scratching during assembly.

Try experimenting with other colors or even RGB LEDs for a fun twist.

Here’s the final Blue Spirit hairpin in action. It’s a subtle cosplay accessory or just a cool wearable piece for fans of Avatar. I learned a lot about iteration, modeling, and simple circuits through this project—and had a blast doing it!