I'm guessing instead of pressing keys, you move your fingers while they're inside the box
It's actually much simpler! It's long, thin metallic switches that you press with your finger tips. They are positioned in a way that you'll curl your fingers in a similar way to what is displayed on screen. It was made using an Arduino Uno kit, it's not overly complicated but still very effective at creating a sense of unease through it's presentation/tactility.