This one is built off a four patch unit. That means each subunit will measure 3.5 inches.
Start with three 1.5 inch strips. If possible find a light, medium and dark. Each strip needs to be at least 14 inches long. If you don't have scraps that long, you can use two 7 inch strips or even four 3.5 inch strips. Sew the strips together and iron toward the dark. Press carefully to avoid distorting the strip set.