The present invention relates to a method for providing a product viewing window in a container. The container has at least a body ply and a liner ply, wherein the body ply has at least one aperture therethrough. The liner ply is adhered across the aperture, forming a window into the container. A window-finishing machine that comprises at least two platens and, optionally, a machine pocket positioned between them, a heating element extending through at least one of the platens, and a pressurized air device engages a container. The heating element heats the window of the container to the desired temperature, pressurized air is injected into the container such that the window is forced at least partially through the aperture of the container (and optionally into contact with the machine pocket wall), and the container window is then cooled to the desired temperature.