I was recently commissioned to make a mask from Tokyo Ghoul. The mask is Enji Kouma's red Devil Ape mask. I opted to buy a cheapo mask replica from a Chinese retailer and fix it up to save on design time and costs.
here is the original:
I had the idea to add leds to the eyes to mimic the character's eyes. I tried both white and red leds. The white were very bright in the eyes, and the client liked the red effect anyway.

After taking the mask apart, the next order of business was to rebuild the parts. First was the teeth. The original was just white foam with teeth lines drawn on it. I cut out the lines and split the foam into individual teeth. I then gave it a layer of brown paint for base coloring before airbrushing them white again. I traced the insert onto another strip of foam and painted that one black for background coloring.

I replaced the faux fur with a thicker, cleaner white version. Weathering was added using black shoe polish in the crevices.




Here is the mask reconstructed without the eye leds

The mask wiring exposed. Its a simple battery and led circuit. In each eye are two leds in parallel. The eyes are both wired in parallel with a 330 ohm resistor so the batteries don't blow out the leds. A switch and 3d printed mouthguard can be used to turn the eye effects on and off without using your hands.

The final mask setup with the eyes on

And a video showing the lip switch operation
And as a bonus for my client, I made a tail using wire hangers and some leftover faux fur