This is my lovely landscape, featuring a seamless pattern I created, used in different sizes and opacities. This was an interesting assignment, and I can see where it would be useful (although time-consuming!) in creating exactly the type of pattern needed for a project. First, you create your squiggles in a rough square, using the Pencil or Brush tool (I used a simple brush stroke with a bit of a "tail" for interest). After Rasterizing, set options for Live Trace, previewing the effects until it looks the way you want. There are a couple of other steps, but the really time-consuming part comes after cropping with Pathfinder. The block of pattern is duplicated and shifted to the left, then the direct selection tool is used to line up points (lines) with the original pattern block. This process is then repeated after shifting the duplicate to the bottom, and then, you should have a seamless pattern when it is used as a fill! Using the "interesting" brush stroke made lining up some areas a bit of a challenge, but overall, I think it turned out pretty well.