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!

Supplies

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

Step 1: Finding the Right 3D Model

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.

Step 2: Preparing Your Print in Cura

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.

Step 3: Printing and Iteration

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.

Step 4: Sanding & Painting

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.

Step 5: Adding the LED Circuit

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

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

Step 6: Final Assembly

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!

Step 7: Reflections & Tips

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.

Step 8: Finished Product

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!

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