My son (5 years old) is buildi

My son (5 years old) is building a "robot" with recycled material, like toilet paper tube, popsicle sticks, used sheets of paper, boxes, bottles, etc., and one of this days he cames to me and ask when I will be adding the cables for the robot to move by itself... ??. So, I'm thinking in adding some basics movements to his robot, like moving one arm just up and down, adding wheels, and so on. Now i'm wondering what will he be asking when he is around 10 ??