Angry Birds Star Wars Bonus Level #9 (S-9) is unlocked by accumulating a total of 555 stars. Once you have accomplished this task, you will be prompted to play the level right then and there, or, you can access it via the “Bonus Episode”. To 3-star S-9, toss C-3PO between the west and north structures, detonating him to bring them crashing to the ground. Use R2-D2’s electro-shock to pop any remaining pigs.
Go back to the Complete Star Wars Golden Droids & Bonus Level Guide. If you have a different strategy feel free to leave a comment below; however, don't just post your score via the comments, as that's what the leaderboards are for.