This project is great for cosplay and looks amazing both in person and in photos. Soldering wires to the tiny NeoPixel LEDs is definitely challenging, but with a magnifying glass and some patience, it's doable.

This build is inspired by the music video for Spring of Life by my favorite J-pop group, Perfume. In the video, directed by amazing media artist Daito Manabe, the singers have LEDs mounted to their nails with white wires gracefully falling from each finger. Originally, I recreated this look with SMT LEDs in just one color. In this guide, we'll take it to the next level with NeoPixels!

Keep in mind that this is really an art piece and not practical to wear in any way. Wearing this project involves temporarily attaching LEDs and wires to your hands, so it's quite a commitment to wear it out to an event. While loose wires look awesomely cyberpunk, they can easily snag on just about anything, so be careful. Also, you should not get your hands wet while wearing this. Plan accordingly! That being said, I wore this for a few hours at a wearable art show opening and had a blast.

Parts & Supplies

• NeoPixel Nano 2427 RGB LEDs x5 LEDs per hand, plus extra for solder practice
• Silicone Covered Stranded-Core Wire
• Gemma M0
• 3.7V 150 mAh LiPo Battery
• You also may need a Micro Lipo charger if you dont have one, for recharging the battery
• Super Glue
• Acrylic Nails and Adhesive Nail Stickers Brush on epoxy, such as XTC-3D by Smooth-On
• 2" Elastic or premade wristband or fingerless glove
• 1" wide sew-on velcro
• Acetone for nails

Tools

• Foam Core or Cardboard (a small piece)
• Carpet Tape or Double Stick Tape
• Removable Mounting Putty or Blu-Tack
• Lighted Magnifier
• Soldering Tools & Supplies
• Helping Third Hand Tool
• Hand Sewing Kit, Sewing Machine (if you have it)

The circuit we are building is simple: basically, we are connecting a homemade strand of NeoPixel LEDs to a Gemma M0. The illustration above shows the general connections we'll be making, but is not to scale, and not representative of the actual connection points in the strand. See the diagram up top for help locating the correct pads on each NeoPixel.

Connections to the Gemma M0 are as follows:

It gets complex when we start building the strand of NeoPixel LEDs. We'll chain the tiny NeoPixels together, sending power, ground, and data from the thumbnail to the pinky nail. Note the layout of the pads, and look for the cut corner at the top right on the front of the NeoPixel. Use this corner to orient the NeoPixel correctly while making your connections in the next step.

Let's build the circuit!

Measure Your Circuit

Start by making a template of your hand. Place one hand on a piece of paper and trace all the way around it. Next, mark the placement of a NeoPixel on the tip of each finger, and the location of the Gemma M0 on your wrist. Draw the path of the circuit, as shown, starting from the Gemma M0, and ending at the last NeoPixel on the pinky.

Now, measure your line to determine the lengths your wires should be. Add 1 - 2" to each length for ease of movement. Add 3-4" to the wire going from the Gemma to the thumb, trust me, you'd rather have too much here than too little. For reference, my measurements were:

Gemma to Thumb: 8 1/2"
Thumb to Index: 8"
Index to Middle: 7"
Middle to Ring: 7"
Ring to Pinky: 6 1/2"

Prepare Your Wires

Cut power, ground, and data wires for each length needed. Label the wires with removable tape to keep everything organized while working.

Strip both ends of each wire. The pads on the NeoPixel Nano LEDs are super tiny, so you only need to strip a tiny bit of insulation off the ends of your wires.

Make a Sticky Card

Cut a piece of foam core or cardboard about the size of a business card. Apply double stick tape to one side as shown. We'll use this sticky surface to hold the NeoPixels and wires in place while soldering.

Slide the card into a Panavise Jr. (or just affix it to your work surface) and position it under your magnifier.

Soldering Tiny NeoPixels

Soldering these tiny NeoPixels is delicate work. Don't linger with your soldering iron, it's easy to melt the plastic and destroy the solder pads. Be deliberate, and expect to sacrifice a couple of NeoPixels while you hone your technique.

Remove one NeoPixel Nano from its packaging and pick it up with tweezers. On the front of the NeoPixel, one corner is cut. Place the NeoPixel face down on your sticky card as shown, with the cut corner at the top left.

Carefully tin the pads with solder. A very light tap of the hot soldering iron on the pad should be enough for the solder to adhere. If you have a fine tip for your soldering iron, it can be helpful.

Solder the Wires

Tin the wires. Lay the tinned wire on top of the tinned pad. Use your heated soldering iron to briefly press the tinned wire to the solder pad, the solder will flow quickly. Don't linger! Repeat to attach wires to all the pads as shown.

The first NeoPixel (for your pinky finger) will only have three wires coming from it, but the rest will have six: data in, data out, two power, and two ground. Data in and data out are pretty straight forward, but here's my technique for soldering two wires to these tiny pads:

Use tweezers to twist the two power (or ground) wires together tightly. Tin the twisted wires. Lay the wires over the pad as you've been doing, and solder as before. Soldering the thicker bundle of wires will take a millisecond longer than the single wires, but you still want to move quickly.

Continue soldering the LEDs together keeping the wires in order, until you've connected all five NeoPixel LEDs.

Connect the Gemma M0

Once you have all the NeoPixels soldered into a chain, you're ready to connect them to the Gemma M0.

Set the Gemma M0 in the helping hands. Solder your wires as shown: power to Vout, ground to Gnd, and data to D1. 

The Gemma M0 can be programmed with either the Arduino IDE or with Circuit Python. For everything you need to know about programming the Gemma M0, visit the handy Gemma M0 guide!

To make it super easy, we'll be using CircuitPython, which comes pre-installed on the Gemma so no special IDE or compiler needed!

Many existing NeoPixel strand animations will work with this circuit, just change the data pin in the code to D1, and set the number of pixels in the strand to 5. I like the ombré rainbow animation in the Circuit Python NeoPixel sample code by Phillip Burgess.

Here's how I modified that sample code to just show the rainbow animation, which looks great when photographed:

I grabbed the code from the link above and pasted it into my code editor. Then I scrolled down to line 35 (see above). Lines 36 through 46 fill the strip with a single solid color, so I commented them out. Now the loop skips directly to the rainbow animation and plays that continuously. I saved this code onto my Gemma M0, and boom: rainbows for days! Well, more like an hour or so.

This animation is great for a photoshoot, where it's nice to have the LEDs lit constantly and predictably throughout the shoot. However, with such a tiny battery in this project, you'll get significantly more wear time if you build some kind of blinking action into your animation. So get creative here!

Prepare the Nails

I like the look of clear nails for this project, but you can use any color of acrylic nails for this. You'll need to cut, shape, and file the nails so they will fit nicely on top of your own nails. Take your time with this.

Set the acrylic nails out in order from thumb to pinky. Use the mounting putty to stick the pinky nail to the end of your third helping hand tool.

Apply a small amount of super glue to the back of the pinky NeoPixel and press it in place on the nail. Hold it in place for about 15 seconds (or check the set time on your glue). I found that the cyanoacrylate glue that came with the nails was fantastic glue that set very quickly, so you might want to use that if you've got it!

Repeat to attach each NeoPixel to its nail. When the glue has dried, it's a good idea to coat each nail with epoxy for added security and strain relief. The clear epoxy also makes the nails shine like glass!

Apply the Epoxy Coating

Prepare the nails to be coated by taping them to a piece of cardboard so that each nail is held off the edge of the cardboard as shown. Make sure the nails stick straight out, and are not angled, or the coating will be uneven.

Follow the manufacturer's instructions for mixing up your epoxy coating (I used XTC-3D by Smooth-On), and brush a solid coat onto each nail. Check all sides to make sure the epoxy covers the whole nail and sucks into the crevices between the wires.

Set this to dry and cure as directed by the epoxy's instructions. While your epoxy is curing, you can work on your wristband or find a fingerless glove to hold the Gemma M0 and battery.

Wristband or Glove?

The wow-factor of this project is in the way the lights are mounted directly to your fingernails, and a fingerless glove will give you a surface to mount the hardware to, while keeping your nails accessible. If using a glove, sew the Gemma to the back of the hand, then use small stitches to tack the wires to the glove to keep them tidy. You'll also need to sew a small pocket into the palm for the battery.

Alternatively, a wristband is a nice option for keeping the hand visible, for more of a cyberpunk manicure look. The wires are more freeform here, so be careful when wearing this to avoid snagging. Here's a quick and easy way to make the perfect wristband for your manicure:

Make a Wristband

To make a simple wrist band, use 2" wide waistband elastic. Measure your wrist circumference and add 2 inches for an overlap. Cut a piece of your elastic to this length. Sew velcro onto each end to make a closure. Remember to put the velcro on opposite sides of the elastic so that they meet when the wristband is closed.

Add a Battery Pocket

Cut another piece of elastic about 2 inches long, we'll use this to  make a battery pocket. If your epoxy is still drying, mark out where the Gemma will go on the wristband - it should sit on top of the flat part of your wrist.

Place the pocket on the wrist band next to where the Gemma M0 will go, and try to position it so that the battery will sit flat against your wrist. Sew around three sides of the pocket, leaving the top open.

Sew on the Gemma MO

When your epoxy is fully cured, center the Gemma M0 on the wristband, with the JST connector pointing up. You can use a dab of hot glue to hold the Gemma in place, then hand sew through four of the sew tabs to affix it securely to the elastic. 

Tuck your battery into the pocket and plug it into the Gemma M0. Turn your Gemma M0 on and check out your rainbow manicure!

Wear It!

To apply the nails, I recommend using adhesive nail tabs. You don't need super strong adhesive, since you'll likely only want to wear these for a few hours at a time. These tabs can be removed with a few drops of acetone, which should not harm the epoxy coating on the nails.

For removal, use a cotton swab to apply the acetone one drop at a time to the adhesive sticker, and gently remove the acrylic nail from your nail.