One of the experimental humanoid robots from Kyoto University. Royal can kick a ball, lay down and stand up on its own from a lying position.

Alan Federman, a former NASA robotics specialist, is trying to get kids interested in building robots by showing how they can be built out of household stuff. “Everything except for the control system you could get at Home Depot or a junk yard,” he said. He’s also working on one that could be operated with commands from a mobile phone. He used wood because the first model, crafted from PVC pipe, cracked.

This robot, from a hobbyist, uses a Nintendo Game Boy as its processing unit. The robot can navigate along a black line or chase a nerf ball.

Carnegie Mellon University developed these robots to show how bots can be built out of wood and other ordinary items. A kit costs about $3,000.

The PackBot from iRobot. It can climb stairs and carry a camera on its arm. A few have been “killed” in action in Afghanistan.

A robot made of Legos determines the perimeter of a black circle. Lego has created several robot kits for educational purposes in its Mindstorms program.

Let the battle begin. This 1-pound robot fights others by wedging underneath them and flipping them over. Other robots come with rotating blades and bulletproof glass. Weight classes range from a pound to more than 200 pounds.

Danger, Will Robinson! Don’t be fooled. This is actually a mock-up of the Lost in Space robot. You can also buy body doubles of Robby the Robot from Forbidden Planet and C3PO.

Fear not the Robonova-I from Hitech Robotics. The $1,000 robot, coming out in about 30 days, can perform a number of tricks.

Robert Fisher and Michael Sohn, juniors in Cupertino, Calif.’s Homestead High School, show off a robot they made that can pick up small objects.

This robot, which earlier roamed at Burning Man, expresses a common sentiment at Robonexus.