Here is a little checklist of what you need.
This is a detail and you can see how imperfect it is some times seeing the pencil lines... 
1.We went to home depot and had 4 1x10 pine boards cut all 5 feet long. (The more knot holes the better) 2. On a flat surface lay them side by side. Use 3 1x4¹s to hold the boards together. These can be nailed or screwed it. The big boards are horizontal and the 1x4¹s are vertical.
3. Sand the edges of the flag.
4. Draw your outline (stripes etc.) in pencil on the wood
5. Prime the front and sides of the flag with orange shellac. This should dry in about an hour. (This will make the wood a little darker. If you want the wood to be really dark you could stain it first and then seal with the orange shellac)
6. Paint the front of the flag with crackle medium. Follow the instructions on the can. When it is dry you paint on your red, white and blue. The variations in brush strokes and thickness of paint will give you different effects. Enjoy the process and don't worry how it is looking. We are going for rustic here. You might want to do the red and let it dry before doing the white. You don't want to have the wet colors touch each other.
7. When the blue is dry you can add the white stars. I did mine free hand but you could also try a stencil.
8. When it has been dry for a day you can add a layer of paste wax made for dark furniture. Follow the directions on the can. But basically you add a thin layer with an old cloth, let it dry for 20 min and then polish.
(If you need a different size just use smaller or less boards. )
If you give it a try I would love to see a photo!
Happy almost 4th of July!
