Bad Piggies Flight in the Night Level 4-34 can be three starred using a single contraption. A simple 3-metal-box contraption with a blue firework can earn 3 stars with a little luck. As the cart descends the hill, activate the firework to blast over the Angry Birds and onto the finish line.
If you have a different strategy for completing this level feel free to leave a comment below.
I Prefer Using The Red Rocket To Go To The Finish Line
Using Blue Rockets Are More Harder
A 4-box contraption (wheel&egg/pig&blue rockets/box/wheel) too work, activating the rockets as in the video
I used two boxes in a row, with the red rocket attached to the left, and the blue rockets on top and under the left box. May take a few tries, but no wheels necessary.
Like video, but egg in center box. Seems to change balance enough to get over line more reliably.