Cut out freezer paper pieces, and iron to the reverese of the desired fabric, in this case a background print. Leaving the freezer paper on the fabric, cut out leaving a 1/2" seam allowance all round. This generous amount gives you a little wiggle room.
Place on to your foundation pattern and sew as you usually would, it helps to leave the freezer paper on to identify the pieces as you go.
You can see how the fabric for piece A3 is ample size and opens out to cover the area and the 1/4" seam allowance with a little extra left over.