The MP-5 is already packaged in robot mode.
Customs x-ray scanner operators were obviously educated to be able to pick out a robot mode MP-5 from x-ray scans of sealed postal packages. They weren't looking for the silhoutte of a gun on their monitor screen, but one biped robotic toy out of the thousands of biped robotic toys that pass through their x-ray scanner. And the only thing that would tip them off would be outlines of a gun barrel, scope or trigger - nothing much else stands out from an MP-5 silhoutte that shouts out it could turn into a gun. This in addition to the thousands of other specific contraband items they have to look out for each day, I was really amazed that they managed to find and confiscate so many MP-5s.