I use photoshop for all my work. The center line is three bubbles to start and the way photoshop works is the top of one bubble snaps to the bottom of the other and the other two snap to the center where the others join (hope that makes sense). Then I just repeat this for the other rows . The the rows won't snap to each other so its by eye with careful nudges. This is actualy not perfectly aligned but its pretty close. Thanks very much for the compliment! I aim to improve all the time.