Yesterday at Re:Publica we came across a little booth to make your own signal blocking pouch for your mobile. In short: even if your phone is switched off, it is still traceable. By putting it in a Faraday cage, you render that impossible.
In this little DIY booth, you could make your own mobile phone pouch from a cloth with metal weave, thus creating a Faraday cage. The material is actually sold as a layer for beneath your carpets and behind your wall paper to reduce em-signals in your home.
With a 10 minute effort, we cut the cloth, stitched it together with pins, and ran it through the sewing machine (a first for me 😉 )
The guy behind the booth pitched it as “perfect for during your next protest march!”. So if I ever end up in one, I will know how to make my phone invisible to police monitors ;). And you can do the same! Find instructions at Killyourphone.com. I wonder if they will detect it at airport security.