I liked the idea of having a custom LED display in my car to send notices to the person in the car behind me.
The CarSwitch is a Particle Photon connected to five buttons which are mounted in a custom case. Additionally a DFPlayer Mini is connected to the photon to play funny sounds by pressing a button. The LED display supports scrolling text, static text and different colors.
Unfortunately custom LED displays are not allowed in the traffic rules so the display is not connected to the photon while the CarSwitch is mounted inside the car.