If you go onto youtube you can find out how to make a faraday cage out of a metal garbage can. Basically, it has to be an airtight lid that fits the can. The metal can has to be lined with cardboard inside...also line the inner lid. You can then put in any of your small electronics, such as laptops, radios, batteries, etc. The way that he tested it, was to put in a radio that was on, and when he closed the lid, it wouldn't work because it wasn't receiving the frequency. My hubby and I made a couple of them for our electronics. Hope this helps!