What is a good homemade toy for a toddler?

I am in a child development class for school and we have to make a child's toy. What toy is easy to make that also allows the child to learn and interact with?|||How about a simple puzzle made from foam or cardboard. Shape sorter toys can be made easily. You can take a shoe box and cut holes in the top the same shape as your child safe objects. You can use blocks, toilet paper tubes and any object large enough they cant choke on for shapes. You could make a sock puppet and make a little play.