As mentioned, I get happy with lighting on my projects. Arduinos lend themselves very nicely to these programmable LED strings popularly called "NeoPixels". Instead of a star topology where you have to wire every LED back to some central point, you just wire the RX to a controller (in this case, an Arduino), which goes to the first LED, to the second, etc, in a line. Makes the wiring much tidier.
These LED's come in several forms; the traditional round style in multiple sizes, flat ones, bars, and various shapes. One of the latter I enjoyed is a small circle:
which can be programmed as a strobe (slow motion)
End result:
https://youtu.be/IeSNXUt1nA4
The LED's aren't actually limited to yellow or white, they're full RGB, so you could just as easily do red or blue or whatever for emergency vehicles
https://youtu.be/o6m2hWx5NkE
And, because they're software-driven, making blinking patterns or traffic directors or strobes just requires different programming, no hardware changes.
Here's the backup lights; center of the rear bar stays white, and corners and the edge markers strobe.
https://youtu.be/SD8kimBdvOQ
Brake (center red) and left turn (sequenced)
https://youtu.be/eJ4eigj61xc
And traffic director when loading or unloading
https://youtu.be/AndqlGcuIp8