The power went out in my residence not too long ago; it was evening, and very dark. To my surprise, one room was emitting light; it was a vase that I had printed in Glow-in-the-dark Green PLA. Surprisingly it allowed me to navigate the room with ease. Anyway, as a result, I printed out a few signs, and placed them around the house with 3m wall tape (removable adhesive strips) to help illuminate the place for the next power outage.
Once I started making symbols I just went all out.