Bad Piggies Rise and Swine Level 2-14 can be 3-starred using a single contraption. Build a three frame cart with the grappling hook in front. Pull the contraption up the hill a little and let it roll back to collect the star. Then again all the way up, and time the last pull so that the plunger hits the star before reaching the finish line.
If you have a different strategy for completing this level feel free to leave a comment below.