Connections
Oled
Display SDA -> Arduino A4
Display SCK -> Arduino A5
Display GND -> GND-USB-Cable
Display VCC -> VCC USB-Cable
Sensor
Sensor PWM -> Arduino D7
Sensor GND -> GND-USB-Cable
Sensor Vin -> VCC USB-Cable
Arduino
Arduino Vin -> VCC-USB-Cable
Arduino GND -> GND-USB-Cable
RGB LED
WS2812B RGB LED data PIN -> Arduino D8
Case https://www.thingiverse.com/thing:4583703
Sources: http://www.holzwertiges.de/home/co2-sensor https://esp8266-server.de/CO2Ampel.html