This Instructable will explain how Cameron Spitzfaden (a sophomore at Alma College) and myself (a senior at Alma) created an animatronic monster for a class project and short film from start to finish.

We used a wide variety of materials to create this:

3D printer
An Arduino
Bread board
Nylon hinges
Nylon control horns
Four servos
PVC foam board
PVC
Music wire
Small screws, nuts, and bolts
Two Joysticks
Glycerine
Gelatin
Honey

UPDATED: Added two videos, one of the complete animatronic, and the other of just the eyeball from when we put it together.

Step 1: Frame Design

We built the monster's frame from three circular platforms of decreasing diameter. We cut them from PVC foam board and drilled a hole in the center of of each. We mounted them onto a central column of PVC tubing using cable connectors. These platforms provided mounting surfaces for the eye and mouth mechanisms.

Step 2: Eye Mechanism

We based the eye mechanism on Micropuller's animatronic eye mechanism 3-D model found on Thingiverse. We printed the eyelids and universal joint as-is. We rotated the eye model so it would print with the round side up. We trimmed the frame down to just one eye, and we left a section with which to attach the eye mechanism to the platform.

Rather than mounting the servos in the eye mechanism frame, we cut holes in the platform and sank the servos. We connected the servos to the eye and eyelids using music wire and nylon connectors. We aligned the servo arms such that the eye mechanism was in its neutral position when the servos were centered.

We found the eye to be ever-so-slightly too large, and it did not rotate smoothly in the eyelids. We used a Dremel tool to grind out the inside of the eyelids.

Step 3: Mouth Mechanism

We cut some PVC foam board into two arc-shaped plates. We bolted one directly to the middle platform of the monster frame. We articulated the other below it using nylon hinges. We attached a control horn to the lower jaw plate and used more music wire to act as a pushrod. Finally, we cut some teeth from sheet polystyrene and glued those to the edge of the jaw plates.

Step 4: Control

We connected all of the power leads for the servos using a breadboard. We connected each servo's signal connector to the Arduino's digital outputs (eye x-axis, digital pin 9; eye y-axis, digital 10; eyelids, digital 11; and mouth, digital 5). We used another breadboard to assemble a controller. One 2-axis joystick provides x- and y-axis motion of the eye. The second joystick controls the eyelids and the mouth. We joined the breadboards using an ethernet cable with the connectors removed. The joystick board connected to the analog inputs of the Arduino (eye x-axis, analog 2; eye y-axis, analog 3; eyelids, analog 0; mouth, analog 1).

We used the Arduino integrated development environment to program the control software. The built-in servo control library proved useful. The default range for the servos is 0° to 180° We adjusted the range for each servo to a value less than that in order to avoid having the servos damage the mechanism by turning too far. The code is available as an attachment.

Eye_Knob.zip
Download

Step 5: Constructing the Monster

In order to make a flexible skin for the animatronic, we first needed to make a sculpture. To save money we built the shape out of a bucket and a ball, and then wrapped wire around that. We then took cheap clay, and made a base layer to work off of. From this layer, we built up the detail and the features of the monster.

Step 6: Latex Mask

Once the sculpture was complete, I made some gelatin latex based off a recipe by fellow instructables member Marshon: https://www.instructables.com/id/Using-gelatin-for-...

The standard method for mask making is to make a plaster cast to lay your latex, but we were having too hard of a time with the plaster casting (it was our first time) so we painted the latex onto the sculpture. The first time did not work, it was too flimsy and tore itself apart. For the second attempt, we used cheese cloth and latex and this worked better, but it still didn't work well. We stuck with this plan however, and used more cheese cloth and latex and this worked for the final product.