1. Paint or stain the mullion strip wood.
2. Decide if you want 4 over 4, 6 over 6, 9 over 9, Victorian, Diamond, etc. design.
3. Cut a piece of white shirt cardboard or heavy paper to fit over the acrylic pane inside the wood frame.
4. With a ruler and pencil, draw the pattern for the mullion on the piece of cardboard or paper.
5. Place the cardboard or paper pattern behind the acrylic pane to see if the pattern is to your satisfaction.
6. Measure the mullion sticks.
7. Cut and lay the mullion sticks over the pattern and glue the pieces together. I suggest that you use a piece of wax paper or tracing paper between the pattern and the pieces in order to keep the glue off the pattern.
8. You can use the pattern for all of the windows (as long as they are the same window or same size). This will result in uniform muntin for all of the windows.
9. Let the wooden mullions dry.
10. Touch up with paint if necessary.
11. Then glue the tips to the wooden frame.
Click here for a downloadable version of these tips or click here to watch an instructional video