In Ned's Declassified School Survival Guide, Seth Powers is always (or almost always, not sure) seen with a basketball spinning on his fingers. Did the actor actually do this, or was it done by means of some trick?
A trick ball
The spinning basketball is a motorised prop with a stick through the middle of the ball.
Seth's hand covers the stick and the motor is out of frame, hence why the back of his hand always needs to be facing the camera, and his elbow always needs to be out of shot.
He isn't the only character to use the prop
In other episodes the basketball is simply CGId onto his hand.