Many types of window film are available for a variety of purposes. For this project, Karl chose a simple film that will keep people from seeing in through the windows, but will let light in.
Make sure the windows are very clean and dry.
Cut the pieces of film so they measure about 1/2" larger than the window panes being covered.
Spritz the window pane with clear water, remove the backing from the film and stick the film to the window. The water makes it easier to position the film and helps hold it on the window.
Use a small squeegee to burnish the film onto the window, pushing air bubbles to the edges (Image 1). When the film is firm, flat and free of bubbles, trim the edges with a sharp utility knife (Image 2).
Repeat the process. Attach the other window films in the same way.