You can make anything with enough time and willpower, you can print elastic bands but I don't have any of that filament. I'm pretty sure you can buy glow in the dark rubber bands already.
The purpose of this exercise was to make the cover intentionally affecting the lightoutput, the glow in the dark was just the filament I happened to have in the printer. My purpose was to lower visable light and more importantly stop the light blindness you get with white light, I can shine this at my face in the pitch black and instantly carry on seeing in the dark when it's turned off. I can flash it and see inbetween flashes without waiting for my eyes to adjust.
I use this multiple times every single day, it's the most used thing I've ever printed, the glow in the dark is also perfect for finding the torch if you put it down.