I tried spray foam on a milk jug. Not enough air got to it. The foam collapsed and ended up like soup. Maybe if you poked breather holes in it the trick might work.
Buy the cheap Nerf type foam soccer balls and poke a hole through it for a rope. Cut the rope long enough to have about a foot and a half "tail" to grab onto after poking it through the ball and knot each end so the rope won't pull out of the ball (a makeshift plastic washer helps)
Grab the tail and slingshot the ball (David and Goliath type of slingshotting) for some good distance tossing and have at it.
Take it stumping with you, too. If in a hilly area, toss it uphill and shoot at it as it rolls down.