Mechanical lottery ball machines are the most popular. Why? It is interesting to watch how the numbers are selected. The draw with a mechanical lottery machine is more transparent. The players can see exactly how the mechanism is working and watch how the balls come out of the lottery ball machine. The players can see the lottery balls all the time during the draw.
A popular type of mechanical machine is the "gravity pick" machine. This machine has a drum with arms rotating inside the drum. The balls go to the drum from the balls container. The drum has a hole, and when the gravity pushes the ball with the lottery number to the hole, a ball goes to the special tray for the winning numbers.
This type of lottery ball machine is used in, for example, Powerball, Polish Lotto or MegaMillions lottery.
The random numbers generator is also used in the world of lottery. Winning numbers are selected by a computer with specialized software. It is a cheaper solution than mechanical lottery machine, in which the organizer has to replace balls and mechanism from time to time. For the players, this type is not interesting to watch and most of the players do not believe that the lottery with random numbers generator is not falsified.