You use the inside of an umbrella and use a circle thing to close it
How To Make A Prosthetic Hand For A 7th Grade Science Project?
I'm looking for the same thing. I was planning to use either duct tape or something strong like that to attach two yard sticks on either end of a clamp's handle and operate it with the yard sticks...but evidently our's has to be operated with string or cord. Poo on my science teacher. Hope this helped.