(Credit: Zain bin Awais)
If you're looking to shield yourself or your devices from electromagnetic fields, a Faraday cage is a potentially useful tool. Use it to prevent thieves from messing with your car key fobs, block NSA eavesdropping (maybe), or just live out your doomsday prepper dreams as you wait for a gigantic, Earth-enveloping electromagnetic pulse to wipe out all electronic communication.
You can buy Faraday cages that vary in size from small bags that hold a smartphone to a Faraday tent under which you can park a car and probably your entire family.
Think you can cook up a solution in your own kitchen using appliances? It's not that easy. A refrigerator or freezer is commonly thought of as an ersatz Faraday cage, but unless the seal is tight, it probably won't work. Likewise, a microwave oven does not a Faraday cage make.
Still, some home items can be converted into a Faraday cage at little cost. Before you put your phone in one, though, put it in airplane mode to avoid battery drain as it searches for a signal.
Think Small
If you're making a Faraday cage for on-the-go, your best bet is to buy one. But you can make a small one. The tinfoil hat joke comes from somewhere, and that somewhere is the Faraday cage. Aluminum foil can be used to protect against electromagnetic fields. Shoplifters use this to their advantage by coating the inside of bags to prevent detection. The same principle applies to this guide on Instructables about using aluminum foil, an envelope, and some tape.
File It Away
A metal file cabinet requires a few tweaks to be turned into a Faraday cage. These directions on Instructables require just a few common pieces of hardware, some cables, and the cabinet itself.
This Is All Garbage
The solution could be in your own backyard. Metal garbage cans—with a bit of modification—can be effective Faraday cages.
Shake It Off
If all this talk of Faraday cages is stressing you out and you want a drink, stop! Your easiest solution is at hand with a cocktail shaker.
Testing 1-2-3
Whatever Faraday cage you choose, test it. Rigorous testing involves a software-defined radio receiver but you can do a simple test by tuning a radio to a station that comes in strong and placing it inside the Faraday cage. Close the cage and if you can still hear the station, the cage is not working.