This seems overcomplicated. Here's a simpler interface: all the numbers in your PIN are between 1 and 8. You view the screen by looking into a binocular scope

This seems overcomplicated. Here's a simpler interface: all the numbers in your PIN are between 1 and 8. You view the screen by looking into a binocular scope. On each side of scope is a row of four buttons where you can place your fingers. The screen displays random permutations of the numbers 1-8, and you select one digit of your PIN from each permutation.