Labyrinths

Labyrinths are levels using a gravity controller to move a ball through a maze to get to the exit/goal.

A couple of ideas:

Moving pieces - You can add pieces that moves when they collide with the ball such as opening doors, gates, etc, or pieces that moves along with gravity, such as "containers" to transport the ball in the direction you want.
Greens - You can add green shapes into the labyrinth or even make the whole labyrinth green to make it harder.
Yellows - Add yellow shapes at some spots inside the labyrinth so the player has to get them all infected...

Some labyrinth levels to get you inspired

The Labyrinth: Stages 01-05: Easy by Golden Actor