I'll get some pics for ya, but my partner has an old axle buried in the ground. It has 2 arms on it. 1 holds the dog on a snap and the other has a small cage on it. We put a chicken in the cage to start the puppies on it and a small pig to start the grown dogs. After they run it once or twice you can do away with the chicken/pig and they'll run on there own. Didn't taken em very long to figure it out and now they have a good beaten down track. It works great, he runs em till they slow down and puts another 1 on there by the time you get done with all of em the 1st one is ready again. They work themselves out.
Thats old school right there, but it works great. They are called cat mills or jenny mills
