A capacitive switch will generally need about three layers to function. A graphical overlay, a circuit layer, and a backing material. The graphical overlay could be any non-conductive material of various thicknesses including; glass, polyesters, polycarbonates, acrylic materials, and many other non-conductive materials. The circuit layer can be a thin plastic flex circuit, or a sensing pad laid out on a rigid PCB. The backing material could be a metal back plate, glass, plastic, or can be adhered to part of your product. It is also possible to adhere a flexible circuit to the inside of a sealed container with a graphic outside to protect the electronics in harsh environments. Capacitive switch constructions can be more complex depending on backlighting options or shielding requirements.