This is my entry for the holiday helper challenge. It is just a little car that has a claw on the front that extends and closes when the A motor turns. It is geared up so it goes faster. The idea is to hide it among the presents with just the ultrasonic sensor peeking out. Then if somebody gets too close it will come charging out. You could put it in a box with just the ultrasonic sensor peeking out and when it sees something it will go charging out a flap in the box. Hope you enjoy it.