Cut the Smoothfoam block down to your desired size using foam cutting tools.

Paint the entire block with white paint and allow to dry.

Then, mask off some lines and a box in one corner for the stars and stripes.

I then glued a star to the center of my blue square and added patriotic ribbon around the outside of my flag. I think the ribbon helped to first finish it off and second helped to cover the uneven cut surface. Both the star and the ribbon are secured with hot glue.