This instructable is about how I built a simple table tennis ball machine

Step 1: List of Items Required:

(For pictures see the rest of the tutorial)

12V Geared motor 45-60 RPM
6V DC motor 13000 RPM
Small rubber wheel that fits the 6V DC motor. I used a wheel from an old tape player.
PVC Pipe through which a ping pong ball will just fit
Wires
9 to 12 V Battery pack
Suitable container (see pictures)
Hot glue gun
Card Board

Step 2: Fit the Pipe to the Containers Base

Cut a hole in the containers base and one end of the PVC pipe so that they fit together. The holes need to be wide enough to let a single ping pong ball fall freely into the pipe. I used my soldering iron to cut out the holes (messy and unhealthy but did the job). Use hot glue to hold the pipe and base together.

Step 3: Fit the Geared Motor

Make a hole in the center of the container and fix the geared motor.

Step 4: Fix the Small Dc Motor

Make another hole in the PVC pipe for the rubber wheel and fix the 6V DC motor as shown. The wheel should enter the hole just enough to brush the ball when it falls through the pipe. Use a generous amount of hot glue to hold the motor securely.

For now I have connected the two motors in parallel using the wires.

Step 5: Attach a Disc to the Geared Motor

Cut a disk out of plastic or hard cardboard as shown and fix it to the geared motor. When the geared motor is switched on, the groove in the disk will pick a ball and dump it into the base hole (watch the video). For now, I used hot glue to fix the disk to the motor shaft. This will actually form a weak joint and might come loose in the future. So I might have to make a proper disk later.