Carefully remove the buttons you wish to replace from your coat using scissors. We need to sew the 3d printed button base to the coat. Start with the very top button, and work your way to the bottom. Place the base part over the area where the coat button was and sew the base onto the coat. You can use normal cotton thread. Once you them sewed onto the coat, test out the coat to see if the buttons are lose enough to button the coat.
The NeoPixels will snap onto the base. Make sure to align up the pin with the holes in the base. Notice how the holes in the base are longer than the pins of the NeoPixel. This is to allow conductive thread to be sewn to the NeoPixels. Make sure the data arrows of the NeoPixels are pointing upwards, towards the top.
Sew NeoPixelsConnect up the power, ground, and data pads on your NeoPixels with conductive thread, securing them inside the bottom half of the button. Take a look at our Conductive Thread guide as well as the Sparkle Skirt and Chameleon Scarf project guides for tips & techniques for sewing pixels with conductive thread.
The stitches should be a little loose, so that the button can lift a few millimeters away from the surface of the coat. But not so loose that the button can twist and short the threads!