I compete in Flyball, and the contrapion is called a flyball box. however unless you plan to do flyball it wont do you much good lol the ball only goes about 2-3 inches and its not easy in the slightest to train a dog to use a flyball box properly and still catch the ball. you would have to take a lot of time to teach a swimmers turn alone, why? because hiting the box with their front paws only puts a lot of pressure on the shoulders and cause injury, a swimmers turn is all 4 feet on the box, that has to be trained speperatly, then you have to start pushing the soring in so that the dog gets used to the bang the box makes when they hit it, then you can start adding the ball after you figer out which way the dog turnes, and teach then to catch the ball lol it does wear the dogs out BUT it also takes a tone of training on your part.

here is a picture of my dog doing a swimmers turn at a turniment.