I have a PlayMate ball machine (which is awesome by the way), but I would love to be able to practice returns, which is by far the weakest part of my game, especially the heavy topspin returns that bounce up around my head. I read that Andre Agassi's dad used to put his ball machine on a ladder for him to practice his returns. Anyone have any experience with something like this? How did you secure it so the machine was stable? Was it effective for you?