The Double Conductivity Buttons or DCB [which is very probably a wrong name for it] were specifically designed for this map. Each button is made of plywood separated in two parts covered with conductive paint that don’t touch each other. Each part is linked by a wire to one Touch Board. This way, when the user touch a button, he activates the two boards at the same time and launches the two relative recordings. To make the buttons more aesthetic, they are also entirely recovered with black acrylic paint.
More about the making process of the buttons : >> Click here <<