Step 1: Plan Your Design

Sketch out the interaction you want to have.

Draw out the mechanism behind it.

Step 2: Let Arduino Talks to Processing

Make serial communications between Arduino and Processing.

Sending data from Arduino to Processing.

So by interacting with the physical potentiometer, it will trigger actions on the processing sketch.

Step 3: Make Your Own Potentiometer

Potentiometers consist of a resistive element, a sliding contact (wiper) that moves along the element, making good electrical contact with one part of it, electrical terminals at each end of the element, a mechanism that moves the wiper from one end to the other, and a housing containing the element and wiper.

Basically a potentiometer consists of a series of resistors, by changing the resistance, it changes the data the device is receiving.

I tried to create my own potentiometers, it worked, but the connection is not smooth enough to create the smooth mountain wave line I intended for my project.

So, I took apart slide potentiometers to ensure continuous connection in order the achieve the effect that I want.