Bad Piggies Rise and Swine Bonus Level 2-III (2-3) can be 3-starred with one awesomely explosive contraption. Start with a row of three steel boxes one in the second row of the grid from the bottom. Then on the far right add two boxing gloves, both pointing up (one glove should go in the far right steel box, and one on top of it). On top of the boxing glove place a pig in one one more steel box. Lastly, on the bottom right drop a plunger wheel. After hit play give the contraption a second to settle, then, whammo!, trigger the plungers to send the pig up to the top of the hill. As he rolls down to the bottom of the finish line he should snag the star box.
If you have a different strategy for completing this level feel free to leave a comment below.