There is a Curious George episode where George dressed up like a robot XF-17. So Son #1 also wanted to label his robot costume XF-17. George also wears a colander on his head so we had to have a colander on our robot's head as well.
DH and I decided that instead of using a cardboard box we would use a Tupperware container, so that it would be more durable. My DH was kind enough to make all the holes and spray paint the Tupperware. The hole for his head was a bit big, so I used some left-over batting to make the hole a little bit smaller and it also provided additional padding on his shoulders. I wrapped the batting in duck tape so it would be the same color and the Tupperware. We used dryer vents for the selves. For the front we decorated a pie tin (idea from Family Fun) and added a reflector light.