Now it's time to solder everything together and fit everything snugly into the housing. Begin by placing all of the components onto the perma proto board and then running wires to the Feather M0 Express and other components. As mentioned in the Circuit portion of the guide, female headers were used for the LCD to plug into so that it can be removed easily and to lift it up high enough for the top of the case.
Circuit layout. Poster tack can be helpful when placing through-hole parts since it keeps everything in place and is easily removed after soldering.
For the individual LEDs be sure to use heat shrink to avoid any shorts. You can use color coded heat shrink to help keep the clear LEDs straight.
After you've finished soldering and have tested everything, it's time to put everything into the housing. First, use M2.5 screws to secure the Feather M0 Express board and perma proto board to the bottom of the case. Also slot the 5mm LED holders into the top of the case. Next, feed the potentiometers and individual LEDs into their holes. Secure the potentiometers with their included washer. Then, press the NeoPixel strip into its slot. Depending on your printer's tolerances you may need to use a small piece of electrical tape to help keep it in place; otherwise the housing should hold the pixels securely. After that, you're ready to close up the case, which should snap shut. With the headers the LCD's screen should be flush with the top of the case and fit properly in its cutout without much adjustment.
The knobs for the potentiometers help in labeling which color is being controlled. However, you may have noticed that there are no knobs with green markings. We can fix this with a simple Sharpie Paint marker. First, tape off the knob so that only the white strip is seen and then go to town with your Sharpie. You can use paint with a brush if you prefer, but the Sharpie is quick drying and less messy.
Once everything is inside the case you're ready to dial in all of the colors of the rainbow!