Start by making a pattern of the window. You already have what you need with the leading lines to design . Take a Sharpie marker and make the lines (lead lines) a little larger.Use freezer paper for you original pattern and then for cutting each piece. Number each piece on the original pattern and transfer onto the background piece. This will keep you from putting something in the wrong place. Use a full cut of black for the background. Then cut individual pieces(different colors) for the glass. Use wonder under for attaching pieces. Layer backing, batting and background. Sew around each piece with clear thread. This doesn't have to be done, but then quilt inside each piece with matching colors. Square up and bind.
I have used this method and have some beautiful wall hangings. It does require some work, but boy the results .....WOW.