Jon Corbett, an engineer who is suing the TSA over the use of full-body "pornoscanners," has developed and documented a simple way to smuggle metallic objects, including guns, through the scanners. He tested the method at real TSA checkpoints, producing video-documentation that shows him apparently passing through the scanners with odd-shaped metal objects in a hidden pocket sewn into his garments. The method relies on the fact that the scanners show subjects' bodies as light objects on a dark background, and also render metal as dark objects. If an object is off to the side of the subject — in a side pocket, say — it shows up as black-on-black and is thus invisible.
To put it to the test, I bought a sewing kit from the dollar store, broke out my 8th grade home ec skills, and sewed a pocket directly on the side of a shirt. Then I took a random metallic object, in this case a heavy metal carrying case that would easily alarm any of the "old" metal detectors, and walked through a backscatter x-ray at Fort Lauderdale-Hollywood International Airport. On video, of course. While I'm not about to win any videography awards for my hidden camera footage, you can watch as I walk through the security line with the metal object in my new side pocket. My camera gets placed on the conveyer belt and goes through its own x-ray, and when it comes out, I'm through, and the object never left my pocket.
Maybe a fluke? Ok, let's try again at Cleveland-Hopkins International Airport through one of the TSA's newest machines: a millimeter wave scanner with automated threat detection built-in. With the metallic object in my side pocket, I enter the security line, my device goes through its own x-ray, I pass through, and exit with the object without any complaints from the TSA.