Eleanor Burns has a method of doing 4 geese at one time and you don't need a special ruler.
1. Cut a square of geese fabric the finished width of the geese unit plus 1 1/4 inches. Cut the sky fabric the finished height of the geese unit plus 7/8". For example: the width is 4" you will cut a square 4 7/8". The height is 2" you will cut a square 2 7/8"
2. Cut one geese fabric and four sky fabrics.
3. With right sides together lay 2 of the small squares on opposite corners on the large square. Using a ruler draw a pencil line diagonally from top left corner to bottom right corner. (See example)
4. Stitch 1/4" from both sides of the drawn line. Cut apart on the center line. Press toward sky fabric.
5. Draw a diagonal line on the 3rd and 4th sky fabric squares. With right sides together place one sky square on the sewn unit. Place it on top of the geese fabric with one corner coming between the sky triangles.
6. Stitch 1/4" on both sides of drawn line. Cut on diagonal line. Repeat for other unit.
7. Press your four geese units. You are ready to use them in a quilt.