A simple six frame animation cycle is what we'll be using for our zoetrope. Here are three really great, expressive examples from everybody's favorite animator, Joe Bowers! Alongside many feature animation credits at Disney and DreamWorks, Joe is the creator of the famous Dovahbear animation series, the beloved Blarbfish, and others. He was kind enough to contribute these three cycles for use in this project. Thanks Joe!
When creating your own cycles, you will want them to hook up from the last frame to the first frame, since they will be cycling over and over. Take a look at the examples above to see how the last frame of each cycle leads back into the first frame. In the second animation, note how the extreme hits on frame four or five and then the smile gets smaller on frame six in preparation for the smallest mouth shape of frame one.
Using a marker, draw your animation frames on each of six ping pong balls. Try to keep the same relative position and size of the drawings so that things don't jitter around too much once the zoetrope is spinning and your eye will see each drawing essentially in the the same position.
Next, we'll create a platform for the heads. Using a compass, draw a circle with a diameter of 6-1/2" onto a piece of chipboard (thin, stiff cardboard). To do so, make the opening of your compass half of that desired diameter, or 3-1/4". Don't cut out the circle just yet, however.
It's very important that the ping pong ball heads are evenly spaced. Otherwise the stroboscopic effect will be difficult-to-impossible to synchronize. In order to do this, we'll divide the circumference of the circle into six even arcs.
The simplest way to do this is to set the pivot point of your compass at any point on the circle's edge and create another identically sized circle. So make sure your compass is still set at the original measurement of 3-1/4" before drawing the second circle.
Now, pick up the compass, place its pivot point on one of the two intersections you just created with the original circle. Draw another circle.
Repeat this process going all the way around the original circle. Look at all of the intersection points between the new circles and the original one -- these are perfectly spaced and now give us our six even sections!
Use a straight edge to connect three pairs of opposite intersection points on your original circle, you will create the perfect indicators of your six sections.
Now, we'll create one more measurement indicator so we know where to exactly place each ping pong ball. Use the compass to again draw a circle starting at the center of our disk, but this time shorten the radius distance to 2". Each intersection with your six lines marks the spot where a ball will go.
Using scissors or a hobby knife, cut out the circle disk.
Now, use hot glue to attach each ball at one of the six intersections, with the faces facing outward from the center. Make sure to place the balls in the same order as your animation cycle!
Push the motor pulley screw through the top of the disk. This will help you center the pulley.
Put a few spots of hot glue on the pulley as shown, and then affix it to the disk.
Once the glue has cured, unscrew the screw, push the hub onto the motor shaft, then drive the screw back into place to secure it.