Does your character really REALLY need to scream? Here's how to greatly expand the range of emotion by making just his mouth and jaw out of clay.
Please see my other tutorials on how to build a puppet and make it talk, as well as many other stop motion subjects.
Software: Dragonframe. iStopmotion (Mac only) is a good frame-capturing app for the price. I understand MonkeyJam is a good free option for Windows. If you have a favorite stop motion app, please tell us about it in the comments.
Camera: I'm using a DSLR. But if you're not there yet, a mobile device running a stop motion app will work fine. For best results, set the camera to fully manual to prevent focus and white balance flicker.
Shopping for Puppet-Making:
Clay (Van Aken, Sculpy III), armature wire, cotton batting to build up puppet: Arts/craft store like Hobby Lobby or amazon.com.
Armature kit: stopmotionstore.com
Puppet clothes (Barbie/Ken clothes: Toy store, ebay, amazon.com
16-gauge aluminum armature wire (from an art store or Amazon, not the hardware store)
Epoxy putty (Hardware store)
Pre-wrap (Sporting good or drug store)
Cotton batting or foam (quilting supplies from craft or sewing store)
For the head, aluminum foil or wood ball (craft store)
Just about everything here can be found on Amazon if you don't have all these kinds of stores in your area. You can also get animation supplies from stopmotionstore.com.