World 3 - Level 5
The Pendulum

There are two ways to stop the Pendulum at the beginning of the level. You can either use the bottom row of boulders (and move it left or right if needed) to roll boulders onto the buttons as the gates become available, or you can jump into the Pendulum and push a boulder into the direction of the other, moving, boulder. The two will collide, and the Pendulum will come to a stop.

To evade the Ghosts, wait until a column has passed, then use a box to build to cross the stream and step on and off of the bridge to make it collapse, trapping the Ghosts behind more water. During your approach to the exit, keep push each boulder and immediately step sideways, as it will roll right back toward you. Get the final boulder onto one of the buttons, and exit.