Metro 2033 Light Sensor

I'm working on a Metro 2033 cosplay costume and being the gadget-geek I am I'd like to make a working copy of the light sensor Artyom carries on his wrist. For anyone who haven't played the game (or read the book, I bought it today but I don't know it he's got the same thing there) it's basically just three LED:s (red, yellow, green) that light up depending on how well illuminated you are (red=fully illuminated=people will see you instantly and shoot, yellow=partly illuminated=people will see you unless you take cover, green=as good as invisible unless you give away your position with noise or flashlight).
In the game it's abut the size of a 9v battery but flatter and for simplicity I'd like to keep it like that; I don't fancy carrying around an Arduino or something like that on my wrist.
Here's a picture:
http://bi.gazeta.pl/im/5/7534/z7534645X,Metro-2033.jpg

So, my question is: Is it possible to make something like that small and simple enough to be stuck to a wristband?

A small micro controller with an LDR and the LEDs and your set. Just program the micro to light each LED as the voltage across the LDR changes. Here is a project similar to what you want.

https://www.instructables.com/id/Arduino-Light-Sens...

Keep in mind arduinos come in all shapes and sizes so you can get one small enough to suit your needs and still read the LDR and light the LEDs.

Jur (author)  mpilchfamily2 years ago

Thank you!
I don't know much about programming (yet) but I think I can get that to work.
Sorry about the late reply, I saw your suggestion but didn't have time to answer and then promptly forgot about it.