Penny for your thoughts

Have you ever seen or made a penny ball? I saw these images when I was checking out Pinterest and thought I can make that. This one sparked my interest, because it could be made with pennies. All you need are a bunch of pennies and an old bowling ball to make this garden sphere, that not only repels slugs, but also makes hydrangeas blue. Or so they say.
I am always looking for something for my granddaughetrs and me to make.
So far its been fun making this project.