Use this simple trick and GIMP's offset function to create a seamless repeat.

You can get a totally seamless repeating pattern with GIMP in just a few
The Tricks and Steps:
- Create a new image
- Pick a color for the background (don't worry, you can change it later)
- Create a new, transparent layer for drawing on and go wild
- Duplicate your drawing layer
- Now here comes the magic: go to Menu, Layer > Transform > Offset (or using hotkeys: Ctrl + Shift + O). You can either enter pixels that you want to move or just hit the x/2, y/2 button and your layer will be moved exactly half its width and length, putting the pattern edges in the middle of the workspace.
- It's very important that the Option Wrap is activated so that part of the image which is moved off the right side of the image reappears on the left.
- Save your design as JPG, BMP or PNG and you're done!
Hurray! Celebrate, upload and print your fabric!
Offizielle GIMP-Seite (englisch)
Last update on 2017-11-09 by Ellie Mutchler.