Able Atelier 3DS is my Homebrew tool I created for 3DS to edit Animal Crossing: New Leaf patterns easier and right on the console.
You can get Able Atelier for your console here, or from Universal DB
Welcome to: Able Atelier! 
Edit Patterns for Animal Crossing New Leaf: Welcome Amiibo directly on your 3DS!
NOTE: Works ONLY for the Welcome Amiibo update, so update your copy of ACNL if you haven't!
SUPPORTS:
- Freely Rotating, Scaling, and Panning the view of the pattern editor (Which ACNL doesn't have in it's editor)
- Pallet swapping patterns
- Working RIGHT ON YOUR 3DS without having to go to an external website to edit your patterns!
Credits
