Unfocused side view of the LED lens and the “touch” sensor. The “touch” sensor is inside the box and look straight up the hole to check if I block the hole with my finger. I use this “touch” to change key to play in, and for the “calibrate” command.
As you may see, the sensor is inside a 4cm tube of shrinking tube so that it can only “see” in a narrow path. This applies to all 24 sensors.
