Create a children's toy form the posted image

Seeking manufacturer to create a children's toy. The category is science/biology/human anatomy. The toy is to resemble the object in the attached image. They toy will be designed to educate children about how the human knee joint works. The child will first assemble the toy, then experiment with and without the round component seen in the image. Specifications: the object is to be made from plastic or other cost effective materials. Need a minimum of 100 sets. As shown in the image, the assembly would require an upper leg piece, a lower leg piece, a round object, and a string or cord. Please view the image: the final product should be able to demonstrate that it is easier to move the lower leg when the round object is in place. The round object represents the knee joint. The entire assembly should weigh no more than 12 ounces. There is no constraint as to physical dimensions, however. For a live view of the toy to be manufactured, please visit [login to view URL]