||To make the block's center unit, sew Color 2 half
square triangles (the ones we cut using templates) to opposing sides
of the Color 3 2-1/2" square. Press seams outwards. Add
two more Color 2 hsts to the adjacent sides, again pressing seams
out. Now add two Color 1 2-7/8" half square triangles to
opposing sides, pressing seams outwards. Lastly, add the last two
Color 1 hsts to the adjacent sides and press outwards...