How to Create a Custom Pattern in Adobe Illustrator

Custom pattern swatches can be created from shapes in Illustrator. In CC versions, a Pattern Options Panel was added to allow greater flexibility.

Most steps in this tutorial are applicable in CS5 and CS6. Exceptions as noted.

1. Create the shape or shapes you want to use. In this example, I'll use a botanical motif.
2. If you are working with multiple shapes using CS versions of Illustrator, you'll also want to create a square bounding box around the shapes. Hold down Shift as you draw the rectangle to make sure it's perfectly square. Set both Fill and Stroke to None unless you want want a color background in the pattern, in which case make sure to position the square behind the other shapes (Object > Arrange > Send to Back).
3. Select all the shapes and drag them into the Swatches Panel.
4. Create another shape and go to the Swatches Panel. Apply the pattern to the Fill.
5. To modify the applied pattern in CS versions, use the Transform commands. For instance, if you want to change the angle of the pattern, go to Object > Transform > Rotate.
6. In the dialog box, turn off Transform Object and check Transform Pattern.
7. Illustrator CC introduced a Pattern Options Panel for global transformation of patterns. In other words, the modifications will be applied to the swatch itself. To modify the swatch, go to the Swatches Panel and double-click the pattern swatch. This will open the Pattern Options Panel as well as put you in Isolation Mode.
8. The Tile Type options let you offset the the pattern repeat, or change the tile shape. There are also Width and Height fields for scaling the pattern. As you can see in the screen shot, you can also name the pattern.
9. When finished editing the pattern swatch, go to the Isolation Bar at the top of the window and click Done to exit Isolation Mode.