Bad Piggies Rise and Swine Bonus Level 2-I (2-1) can be 3-starred using one contraption, but with two turns. Start by building a 2×2 box. Place the pig in the left box, and an engine in the right. Now attach plunger wheels to the right of the engine so that it sticks out to the right, and one below the pig. Complete the first two objectives by rolling as quickly as possible to the finish line (jump the gap!). On your second go don’t jump the gap, rather roll up and around to snag the star box.
If you have a different strategy for completing this level feel free to leave a comment below.