The answer is Half Square Triangles. And I have been cutting, matching up, sewing, pressing, cutting, trimming, pressing again and clipping these little treasures for days! But it still doesn't look like much!
They are sew cute though!
Here is how I make my HST's....
Making Half Square Triangles - A Tutorial
For the purpose of this diagram the right side of the fabric is shown in pink, while the wrong side is shown in white. Please note that the fabric squares should be ‘sandwiched’ with right sides facing together, and line up on all sides as accurately as possible. The diagram does not show this accuracy for demonstrative purposes only.
First determine your finished size square. For my scrappy neutral quilt I am using squares with a finished size of 2". Add 1" to the finished size square to determine how big to cut your pieces. So, I need to work with 3" squares to make my HST's.
Using your rotary cutter and acrylic ruler, cut your fabric along the width of the fabric to make strips measuring 3" and sub-cut these strips into 3" squares.
STEP 1: Take a color square and a neutral square and ‘sandwich’ them together with right sides facing together as shown in Figure A. Using a pencil and ruler, draw a diagonal line on the wrong side of the neutral fabric, from the top corner to the bottom corner as shown in blue in Figure B. This is your guide line. Sew a ¼” seam on the right of the blue line from edge to edge as shown in red in Figure C.
Chain piece your HST's by continuing these steps shown in Figures A, B and C for about 10 other pairs of squares, sewing the seams, and without cutting the thread. At the end of the last seam, turn your chain of sandwiches around and sew back along the opposite side of the guide line on each sandwich square. Remove the chain of squares from machine, bring them to your ironing board and clip the threads between the sandwiched squares. Your squares should all look like the one in Figure D. Press to set the seams.
STEP 2: Having sewn two seams across the diagonal of each sandwiched square, and pressed them all to set the seams, it is now time to cut them along the blue guide line as shown in Figure E. Now to trim each of the resulting triangles to size using your acrylic ruler. Your finished size square is 2", but your unfinished square has two seam allowances, so your UNFINISHED square is 2" plus the two 1/4" seam allowances = 2.5". Measure 2.5" from the seam to the corner, and make sure the seam is at a 45° angle to the sides, as shown in Figure F. The seam will line up with the dots on your ruler. Trim the square.
Now open the triangle and finger press the seam open. Press the seam open with the iron. Flip the unit over and re-press it on the right side. From the right side of the fabric, your square should look like Figure G. Trim the fabric points (dog ears) so that you have a neatly finished square, as shown in Figure H, and…. Voila! Perfect 2.5” Half Square Triangle Blocks!