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!
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.
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:
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.
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.
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!
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.