Here is one finished dementor panel...only fifteen more to go. My method of construction is a bit weird, but this was the only way I could construct this and preserve points. For this to work, I will have to add in a row of sashing strips following the flow of half square triangles, dark and light squares.
As a reminder, at this point I am cutting out triangles to make bat wings. Then a bat wing with a dark square is sewn to a bat wing with a light square. Those squares are my base units. Each section uses 56 of these to make a 7 by 8 panel. (The sample above is a 4 X 4 panel.)