Illustrator Action set (4 actions) will help to create seamless pattern.
Video demo How it works is included
Easy to use
1 .Open template.ai file
2. Load actions
3. Copy paste vector objects or groups of objects. For best result an object should be smaller than 500px wide or tall.
4. Play action.
5. After I stops , use Direct selection tool(A), Free transform tool(E), Reflect tool(O), to move , rotate , flip and duplicate objects if necessary. On the fly you will see all the changes you make to the whole pattern.
6. Pres play button to continue.
7. Save the pattern as a pattern swatch.
Seamless pattern actions.aia
how it works video.avi