This was a fun project and I think the end result was rather creepy. I'm considering what to add next, but some moving teeth are a real possibility. Anyway, I used the Raspberry Pi Zero with the Adafruit Snake Eyes bonnet and dual 1.5" color OLEDs. See some details at https://learn.adafruit.com/animated-snake-eyes-bonnet-for-raspberry-pi
Many thanks to Cporto for the Low Poly Mask design.
Retained the OLEDs using a slightly modified version of the Teensy OLED sandwich mounting. I added a cutout for the top mounted cable pin/socket to exit on the rear piece of the sandwich (Face Backplate). Source files for the original OLED sandwich parts are at: http://www.thingiverse.com/thing:1002413 and lots of helpful text is at: https://learn.adafruit.com/animated-electronic-eyes-using-teensy-3-1/3d-printing .
Many thanks to Pburgess for the original OLED sandwich designs.
I designed a standoff mounting bracket (EyeMount) that positions the OLED sandwich behind each eye on the mask's interior. The two EyeMount standoff pieces are L&R mirrors of each other. Each Teensy OLED mounting sandwich pair is screwed onto its custom L&R EyeMount standoff bracket using four 2.5mm machine screws threaded directly into the EyeMount standoff post's center holes. No 2.5mm nuts were used, I force threaded the mounting screws right into the EyeMount's plastic.
The last step was to glue the four standoff mounting points of each fully assembled eye onto the interior of the mask using a Bondic type, UV activated adhesive material. I used the Bondic stuff because it is a thick, viscous, gel-like material before it is cured, and can be easily built up in layers for additional strength. A quick zap with the UV LED solidifies it almost instantly, and made the holding-things-precariously-in-place-while-gluing-down process somewhat easier. See finished pix of the glued-in eye assemblies on the interior of the mask.
Some info on the display mounting is at https://www.thingiverse.com/thing:2895237
A video of the eyes moving is at: http://www.youtube.com/watch?v=A7F7c4fNFJk
UPDATE: I added some teeth to this odd puppy.
Check em out at: https://www.thingiverse.com/thing:2897334
I used MakerGeeks Maker series PLA "White Hot White" color
A little clean up was required on the mask's eye holes and mouth.
The standoff plates and the Teensy OLED mounting sandwich parts needed drilled out to accommodate the 2.5mm screws used to hold each four-piece display sandwich assembly together. (The assembly stackup consisted of: #1 EyeMount Standoff bracket, #2 Front OLED Sandwich cover, #3 OLED display, #4 Rear OLED Sandwich cover). Each EyeMount bracket is oriented with its most narrow circular cutout section at the top.
Doing this piece in white PLA allowed cleanup operations like trimming or filing without any visible discoloration (typically whitening) of the base material.
I first designed the EyeMount standoff brackets with four, long, equal length, standoff mounting posts. I positioned one of the EyeMounts behind one of the Mask's eye holes, and let the interior mask surface define each of the four standoff post's length and contact profile. I then removed the excess post that projected through the mask's outer face. Lastly I mirrored the finished (trimmed off) EyeMount to create the piece for the remaining eye.