Place a Color 3 3-1/2" square right sides together atop
opposing corners of the Color 1 6-1/2" square,
with all edges aligned. ( I show them staggered here just so you can see that there are
two layers) On the back of the top squares, lightly draw the diagonals then sew ON
the drawn lines. Cut off the excess seam allowance, and press the remainder towards the
outer triangle. Repeat this with two more Color 3 squares on the opposing
corners. Make two units like this...