I developed a good project for this age level about ten years ago for 5th graders, but it was more appropriate for middle schooler, who I didn't teach. It was so popular with the 5th graders, a group of middle schoolers came back the following year, and we developed the project to use in what turned out to be an award winning stop animation film. The project was called "Fuzzy Monsters", and was made from a simple wire armature and fake fur. I presented this at the state level, and it was also a hit with the attendees, and I have shared the lessons with many art teachers at all levels over the years.
Contact me off list if you are interested in the plans.