This can be called a ball machine, be used as an element, or be used as a lift. Here is a guide/tips on how to make one.

Example as ball machine: https://www.youtube.com/watch?v=3njcoDqyo1k

Examples as a ball lift: https://www.youtube.com/watch?v=dET0RMmQSZs

Step 1: Design

Shape
I recommend building an octagon-shaped wheel.

Size
The two most important parts to consider are the width and the radius.

A larger machine is more impressive than a smaller one, but has to run slower.

Elements
Choose some elements which can be used from any angle, such as the Flipper, a Ferris wheel, or an Arm drop.
Also, keep in mind that the machine will inconsistently rotate.

Step 2: Returning Ball to Top

Use hook-shaped paths the bring the ball to the top.

Step 3: Stand

The machine needs to be held above the ground.

Attach a motor and gear to the stand.

Step 4: Counterweights and Gears

Distribute the weight of this machine evenly around the outside. The centre of gravity should be the centre of the machine.

Use gears to slow down the machine. This puts less stress on the motor.

Step 5: Entrance and Exit Tracks

Optional - This is for turning it into a lift.
This is the same as the wheel lift with holes. Make a hole for an entrance track, and a path tilted to the side for an exit track.