In this walkthrough, we've shared how to create patterns in Illustrator, so you can stretch a seamlessly tiled design across any object or background.
How to Create Patterns in Illustrator
1. Although newer versions of Illustrator have a dedicated pattern maker, it's possible to create seamless patterns with any version of the software. First, create a new Illustrator project and make sure that the artboard height and width are exactly the same (i.e. a square). It can be 5" by 5", or 120" by 120", depending on your needs
2. Next, place and arrange various elements on the artboard until you're happy with the layout. When designing a seamless pattern, the elements on the right side must appear on the left side (as well as top to bottom), so they're continuous.
3. To achieve the seamless effect, use the Selection tool to drag a marquee to the artboard's left edge. Any element that extends past the left edge will now be selected. Press Ctrl+C (Command+C on Mac) to copy the selected elements, and then press Ctrl+F (Command+F) to duplicate them.
4. Now, go up to the top control panel and add the artboard's total width (ex. 5 inches) to the X axis by typing in "+5" after the current value. This will move the elements from the artboard's left edge to the right edge, so that it continues from one side to the other. You may need to move or resize neighboring elements so that there's more space between them. As you do this, be careful not to move the pasted elements.
5. You'll need to repeat this process for the other three sides of the artboard. When shifting elements from right to left, or bottom to top, make sure to subtract the artboard height/width from the respective axis value (i.e. enter "-5" in the X or Y section).
6. Once you're happy with the overall design, drag a marquee around the entire pattern and press Ctrl+G (Command+G) to group the elements together. Save a copy of your work, go to the Pathfinder window, and click the "Crop" icon to remove any excess elements that extend past the artboard boundaries. To add your custom pattern to the Swatches panel for future use, just click and drag it onto the panel.
Using the Pattern Maker (Illustrator CS6 and Later)
Select your artboard (or any element that you'd like to tile), and choose "Object" > "Pattern" > "Make" to transform it into a seamless pattern. For more control over the settings, go to the Pattern Options dialog box to adjust the tile layout, spacing, width/height, and more. Any patterns created or edited with this feature will automatically be saved to the Swatches panel.