Your dart is and excellent start, I would just sew in a silver fabric in a V shape at the point of your dart instead of the yarn. How about 2 darts and a dart board. I can't find a ready made pattern for the dart board but it shouldn't be to hard to make one up. With paper piecing you could make the black, white and red wedges then embroider the numbers on. I'll keep looking for a pattern that can be modified if necessary.