You can buy Faraday cages, but what fun is that? Whether you want to keep your devices secure during a protest or are just prepping for doomsday, here's how to shield your gadgets from electromagnetic fields.

Protests against police brutality are currently taking place across the country, and while technology has been helpful in organizing them, it can also be used against those in attendance. Facial recognition(Opens in a new window) can be used to identify (or misidentify, as often happens) protesters and phones can be surveilled.

If you're demonstrating, it's a smart idea to take steps to lock down your phone ahead of time or even just leave it at home. If the latter isn't possible, put it in a Faraday cage, an enclosure that shields against the entry or escape of electromagnetic fields.

A Faraday cage is useful for many circumstances. Perhaps you have a car with remote keyless entry, and want to prevent it from getting broken into by teens with a power amplifier(Opens in a new window) . Or you don't want the NSA listening in on your conversations(Opens in a new window) . Or you're a doomsday prepper just waiting for a gigantic, Earth-enveloping electromagnetic pulse(Opens in a new window)  to rise up in the sky and wipe out all electronic communication.

You can buy Faraday cages that vary in size from small bags that hold a smartphone(Opens in a new window)  to a Faraday tent(Opens in a new window)  under which you can park a car and probably your entire family.

If you'd rather not spend the money and think you can cook up a solution in your own kitchen using appliances, it's not that easy. It's commonly thought that a refrigerator or freezer can serve as an ersatz Faraday cage. But unless the seal is really tight, it's not likely to work. Likewise, a microwave oven also does not a Faraday cage make. A police precinct in Greenfield, Massachusetts, tried to prevent the remote wiping of phones it confiscated by placing them in microwave ovens. They found that only commercial-grade ovens worked(Opens in a new window) .

There are still some things you might have on hand, though, that can be converted into a Faraday cage at little cost. Before you put your phone in one, though, put it in airplane mode, otherwise the battery will drain as it searches for a signal.

If you're making a Faraday cage to take to a protest, your best bet is indeed to buy one(Opens in a new window) . 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 into this Instructables(Opens in a new window) about using aluminum foil, an envelope, and some tape.

A metal file cabinet requires just a few tweaks to be turned into a Faraday cage. These directions on Instructables(Opens in a new window)  require just a few common pieces of hardware, some cables, and the cabinet itself.

The solution could be in your own backyard. Metal garbage cans—with a bit of modification—can be effective Faraday cages.

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.

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.

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My title is Senior Features Writer, which is a license to write about absolutely anything if I can connect it to technology (I can). I’ve been at PCMag since 2011 and have covered the surveillance state, vaccination cards, ghost guns, voting, ISIS, art, fashion, film, design, gender bias, and more. You might have seen me on TV talking about these topics or heard me on your commute home on the radio or a podcast. Or maybe you’ve just seen my Bernie meme. 

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All that gadgets is gold for me: my iPhone 11 Pro, my fifth-generation iPad that I use only for streaming videos and music, my iPad mini 4 that I like to take with me whenever I carry a bag that can fit it, and my MacBook Pro. Why are they all different shades of gold, though? What’s going on, Apple? 

None of them quite live up to my two past loves: my LG Lotus LX600 phone and my Sony Walkman NW-E005 MP3 player. 

I've never given up wired earbuds so I was ahead of all those trend pieces. I use a Mangotek Lightning-to-3.5mm headphone jack adapter to connect them to my phone. 

I have had so many ebook readers, but I prefer paper to them all. Still, my Kindle Paperwhite is perfect for traveling or when I’m too impatient to wait for a book to be released in paperback.

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