When my puppy was a mental case, I hung an old garage door spring off a tree limb, attached to a rope, attached to a favorite toy.
He would pull on it for hours while I was in the garage working. Wore his ass right out.
I also put one about 3 ft high on a tree so he could pull backwards/shake it.
He is now 12 and calm untill he sees a rabbit or a ground hog!
No pics cause photobucket
Edit: Found one!!!