The ordered new multicolor RGBW NeoPixel Buttons had arrived and I wanted to replace the monochrome green “LED sequins” for the Alpha-to-Delta lights with them. I started preparing the NeoPixel buttons by carefully filing down the sides to make the buttons more compact.
Before soldering the connections of the Buttons, I stuck small strips of insulating tape between the filed sides to prevent short circuits between the PCBs. I then placed the four buttons on tape to temporarily align them, and soldered the row connections.
Align on tape for soldering 
NeoPixel row placed in the shell 
Top view of the NeoPixel Buttons
The new LED row didn't fit well in combination with the light guides I had already made for the sequins. So I made new light guides for the Neopixels. First I sawed the acrylic profile into short pieces with 45° angles. Then I sanded down the sides and filed a notch to provide additional support when the light guides are inserted into the shell. After wet sanding and polishing all surfaces, I sprayed three sides with white paint.
Profiles sawn-off at 45° angle 
Sawn-off part before filing 
Sanded sides, filed a notch 
Acrylic light guide in place 
Test with LED array: Fits. 
Wet grinding acrylic parts 
Polished acrylic glass parts 
Preparation for painting 
White sides for light reflection
The white painted sides should help to prevent light bleeding at the outside and reflect/diffuse the colored LED light at the inside of the light guide. Later, I also added black PCV to the sides again. But for now, I didn't go ahead with the light guides because I wasn't sure if I would use the NeoPixel buttons that way. I didn't like the thickness and the spacing of the boards when they were placed to the wall of the shell.
