The Overlay comes comes with an acrylic overlay, which is locked in place with a wooden part beneath the playerboard. Three notches come with the overlay, which precisely fit into the holes and lock it together. Some cut-outs are slightly moved, which come from the original player mate design itself. Please be aware of that. If you don't like the divider wall between the Energy and Heat resource bins, just simply break off that wall carefully. A full game requires 5 sets, but you may decide how many you need. We have recieved this pdf, where you could print out fittin player mats for our overlay.