Step 1: Materials
A Parallax USB Servo Controller is the interface between the computer and the servo motors.
Visual Show Automation runs the show & tells the servo controller what to do.
The servo controller circuitry is powered via USB, but requires an external power supply to run the servos.
Audacity can be used to record & edit the sound track.
Step 2: Modifing the Skull Character
Step 3: Making the Talking Pumpkin Character
Cut the pumpkin in half, with a zigzag in the front for the teeth.
Use a straight cut in the back so that there's no interference when the top moves.
Hollow out space for the servo & bracket.
The top is fastened to the servo horn with a piece of aluminum bent into an L shape.
Paint any visible cut surfaces of the styrofoam with a water-based paint (that won't eat away the foam)
Step 4: Creating the audio
If you're going to have more than one character talking, or add sound effects, make sure to keep the voice tracks separate -- more on this later.
In this case, we've got two voice tracks (skull & pumpkin). Export each voice track as it's own wav file, and a third file containing both tracks.