Duck toys - Page 2
My oldest ducks enjoyed playing with the zippers on their baby play pen cover. I bet you could remove the zippers from old clothes or jackets and hang them up inside the pen/coop area for their enjoyment. Or if you're handy with sewing you might be able to make something with a zipper from a material store.
While they're free ranging I toss veggie bits or fruit bits and they'll actually chase after them. Round things like peas/blueberries work best because they roll once they hit the ground.