Algodoo

A box can automatically follow a red circle wherever it moves, with only 6 components!
HOW IT WORKS:
The red circle only collides with layer I, and it has a strong negative attraction.
The laser has a finite velocity, meaning it is repelled by the red circle.
It then hits the semicircle that is further from the red circle, which updates a script that causes the attached thruster to start pushing.
This will point the box toward the target, where it will begin to travel until it hits the target.