Illustrator Tutorial: Halloween Spiders and Webs, Part 1: Spinning the Web

Choose the ellipse tool in the toolbox again, and carefully position the mouse so the cursor is exactly on the top anchor point of the circle. Hold the option/alt key and click. By doing this, you will not only open the ellipse tool dialog so you can set the size, but you will be able to create the ellipse from the center so the exact center of this ellipse is on the top anchor point of the larger circle. Set the size to 50 pixels wide and 50 pixels high and click OK. A smaller circle will be created on top of the larger circle. We'll duplicate this circle around the large one and use them to remove the edges of the large circle to form a scalloped web shape.