Great design! Bought most of the hardware from Sean's etsy shop. Added an Arduino and Burn effects v3 RC Car smoke machine. The smoke machine is connected like a servo. Since doors and smoke make 3 "servos" and the typical servo library is interrupt-wise notorious to interfere with NeoPixels I've put in an extra servo shield. The smoke generator comes with its own controller and gets power directly from the 7.4V LiPo battery. The smoke takes pretty constant 3A. I’ve disconnected the fan from the smoke controller and I am controlling it from the Arduino so I can stop the fan some seconds after stopping the smoke. Main disadvantages are that it's not a closed oil container and that I have to open one side to refill the smoke oil.
All except from the smoke gets power from the battery going through an Adafruit UBEC to get 5V. Sound is also an Adafruit SoundFx board.
Main lights are 3x7 RGBW NeoPixels.
For the front LED I took a bi-color red/yellow. The pedal also has a NeoPixel RBG LED. The pedal LED color and the bargraph indicate the selected song in "disco mode" :) The bargraph can also show the battery voltage that the Arduino measures over a voltage divider. I did an extra push-button on top that just does the same as the pedal. And the extra main power switch (with LED) just cuts off the LiPo completely.
For the connection between pedal and trap I've used mini XLR with 4 wires: (1) GND, (2) switch to GND, (3) signal for RGB NeoPixel pedal LED, (4) Vcc for pedal LED.