You can buy Hall sensors, but making them is far more interesting (and satisfying)! According to the theory, the crucial thing is to use a touch layer that’s as thin as possible. The length and width are unimportant. An ‘obvious’ starting point for our trials would be copper, which in the form of printed circuit board material is easy to find and handle. Copperclad board may be obvious but not ideal, because it has a very weak Hall constant. Nevertheless, we should be able to use it to demonstrate the Hall effect by using very powerful magnets in our sensor.