Measure the window panes using a ruler. Make the measurements exact to avoid any spacing issues when later applying the film to the window.
Draw the measurements of each window pane on clear contact paper using a pencil. Contact paper is an adhesive paper often used for drawer lining. It can usually be found at hardware stores.
Cut the contact paper from the dimensions using either scissors or a cutting blade. Take your time making the cuts, and stay on the marked lines.
Paint a design on the film side of the contact paper with a paint pen. You can paint anything from flowers and stripes to stained glass. To keep consistent, use one color. For more detailed designs, such as stained glass, use multiple colored paint pens.
Let the paint dry for at least 10 minutes.
Peel off the film portion of the contact paper. On the back of the film is an adhesive. Place the adhesive side of the film evenly against the window pane. Repeat the process until all panes are covered. Use a piece of paper to smooth the film on the window to avoid any bubbles.