To sew the block's corner units, sew a Color 3 trap right sides
together to a Color 1 square, (far top left) starting at the top edge
and sewing to a marked point 1/4" from the end of the square.
Backstitch. Sew another trap to the bottom of the square, (near
top left) again stopping 1/4" from the edge of the square.
Backstitch. Press the sewn seams towards the square. Now fold the
square diagonally in half, (bottom left) bringing together the two
un-sewn seams. Starting just where you left of sewing the two previous
seams, backstitch, then sew out to the edge. Make three more units
like this. One will use two Color 2 traps, and two will use one of
Color 2 and one of Color 3... on to Page 2!