My personal favorite training device was something called a crazy ball. Basically its a basketball inside a net bag that is attached to a bungee cord that runs from the ceiling to the floor. The ball goes wild when you hit it and you have to really focus to strike it a second time. I would challenge myself to see how many times I could strike it before I lost control of it completely...which usually wasnt that many times. The time I spent training with this has been quite beneficial to me when I needed it on the street as I learned how to spot openings that I would have missed when I was younger.