Walmart often has somewhat soft foam balls for kids, about baseball size, Some are white and painted like baseballs, others are red or blue.
I buy them on sale, but they are not that expensive.
Take a large spike (nail), heat it real hot and push it thru each one. Then, using a long nose pliers or better, a forceps, push a strong 1/8" cord thru it and tie several knots to make a big knot. The other end is kept long, as much as 6'.
Then I go thru my woods and hang them from branches just off the trails (hang em so they are just off the ground). Use blunts and when you hit them they fly up and around, but generally fall right back to their spot.
I shoot at these from close on out to "where the heck is it" distance, and between trees etc.
There are also smaller green balls, for some little ball shooting gun, that are more ping pong ball sized. I do the same and call these bunnies, for closer shots.
I have seen the same done using bottles, but you tend to puncture them and they are a bit harder to remove the arrows.
ChuckC