Please read all instructions before beginning. All measurements include 1/4" seam allowances, unless indicated otherwise. Try to be as accurate as possible.

Remember the 10" squares of muslin (or other foundation fabric) which you covered with strips during Part 3 of this series? Well, it's now time to dig them out of that pile in your sewing room (you know the one!).

While you're digging, also pull out your 9 7/8" Light squares (remember the ones on which you mysteriously drew a diagonal pencil line?). (Set these aside for the moment.)

Lay one of your strip-pieced units (which you made during Part 3 of this series), muslin side up, on your table. During the process of adding strips to your muslin foundation square, the square probably became slightly twisted, and may no longer be exactly 10" square. This is your opportunity to fix all of that! Therefore, you may now trim it, using your rotary equipment, to exactly 9 7/8" square.

Next, lay one of these trimmed, strip-pieced, 9 7/8" squares right side up. Lay one of your Light 9 7/8" squares on top of it, right sides together. Align it so the pencil line you drew (during Part 2 of this series) is on top of your Medium "Focus Fabric" strip on the strip-pieced square. The pencil line should be going in the same direction as the Medium "Focus Fabric" strip (as opposed to crossing it). Press the layers together, so the edges are as even as you can get them.

Sew, using 1/4" seam allowance, on BOTH sides of your pencil line.

Cut the square in half along your pencil line. You should now have two giant triangles.

Pull the Light fabric back on each of these giant triangle units, and press.

Repeat for all of your remaining strip-pieced 10" square units.