Build your case, fixing the Raspberry PI, Arduino, LCD display, Neopixals plus the RGB strip in place.
The EL panel is installed behind the transparent blue base in my case, this is to protect it, take care with the power connections, making sure that the cable and joints are OK.
Connect the connected the RGB LEDs strips following the screen print markings to the shield, and the Neopixels 5V, 0V to the Arduino’s 5V, 0V and the data in is connected digital pin 12. Using the TLL serial connection on the LCD display, connect the JST cable to the backpack and then connect to the Raspberry Pi's GPIO pins as follows: Red wire goes to +5V, Black wire goes to Ground, White data wire goes to pin 6 (TxD) or you can solder a header on and use jump wires instead.
Fit the power socket and connect with wires to the power in on the Arduino shield, and also feed the hacked 12v to USB converter or the buck converter, use the USB lead to power the Raspberry Pi from the usb socket on the USB converter. Connect the feed for the EL transformer to the socket, you may need to use some form of connector blocks to be connect all the required feeds.
Connect the Arduino SDA and SCL lines to the Raspberry Pi plus connect grounds of both devices together.
Fit and connect the switches, to the Raspberry Pi GPIO pins the red wires goes to a 3v3 pin and the black wires to a 0V pin, The first switch's signal wire is connected to pin 23 and the second is connected to pin 24