Billiards is a popular game with plenty of physics. Unfortunately, because it is only a game, no one has bothered to invent a relatively simple device (compared to all the other physics devices out there) that would substantially help one become better. So I have no choice but to take on the project myself. One of the most important skills in making a successful shot in billiards is that your cue delivery is very straight, like a piston motion. Fortunately, there has been an invention for improving that skill, called the laser cue. By feathering your laser cue back and forth, you can watch a laser spot on a wall. The straightness of your cue motion during the feathering and the cue delivery can be judged directly by watching whether the laser spot wobbles as your move your cue back and forth. So far so good. Unfortunately, this is where the inventions end. The problem is that during a real shot with a real cue ball, the cue ball would be blocking the laser. So this does not help during a real shot. Here are the many problems that a player can have without knowing it: 1) His line of sight is not even in the same direction as his cue during the feathers and cue delivery. Thus, he is aiming at a spot on the target ball that his cue is not even pointing at! 2) During the cue delivery, his cue motion veered to the left or right, and he doesn't know it. Because of this, a player can miss and blame his error in angle judgement when instead the miss might have been due to a non-straight cue delivery. The perfect invention is to have some sort of laser cue that would allow you to see the laser spot on the target ball during a real shot with a cue ball. This device will: 1) Train the player to look in the same direction as his cue. 2) Allow the player to know exactly what went wrong if a miss occurs. Possible inventions: 1) A laser cue that shoots a laser beam over the cue ball and onto the object ball. The problem is that the pointing device would obstruct the player's view when he in the cuing position. 2) Invent a translucent cue ball that allows the laser beam to pass through. The problem is that even the slightest diffraction would cause the invention to be erroneous. Also what the would the material of the ball be? Any other ideas? The bottom line is that I need to invent a device that will allow you to know what exactly went wrong if you miss a shot: Did you miss because you aimed at the wrong spot on the target ball? Did you aim at the correct spot but your cue delivery veered off? Or was your cue not even pointing where you were looking at to begin with? A device that reveals these errors would allow one to improve his game immensely.