This is a very simple trick but one that is very useful for transitions between patterns. The only skill you need for this trick is the ability to juggle Two in one hand & to be able to wave the other ball about. If you can do The Yo Yo you can do this trick.
Go straight in with all three balls. Juggle two in one hand in a columns pattern so that the balls travel up & down next to each other without crossing over. You have two columns, one on the outside & one on the inside. Hold the other ball above & to the side of the two ball juggle. As the outside ball peaks carry the held ball underneath it in a quick scoop, then scoop it underneath the inside ball as it peaks. & so on.
Does this trick really need a tutorial all of its own? Probably not.
As you practise this trick look at your weaving hand. Don't hold the ball right in the palm of your hand otherwise it won't be seen by your audience. Grip it using your thumb, fore & middle fingers only so as much of the ball is visible as possible. Now look at your wrist, if you keep it stiff as you carry your movements will look jerky & forced. Relax your wrist & allow it to curve with the carry.
Be sure to learn this trick on both sides. You can combine the two to juggle a new pattern, Double Eight.