The Psychos in the Borderlands games are maniacs who wear creepy masks with glowing eyes and mouths. Eric of Jarman Props crafted a detailed replica of said creepy masks a few years ago. Using a face cast as the base, he sculpted the mask by hand with all the details before making a mold and casting the finished product. Then the mask went through a few stages of painting to give it the cel-shaded look in Borderlands before Eric added LEDs. You can see a couple of in-progress images below.
More photos of the Psycho mask can be seen in this Facebook album.