10 March 2017

New Version! See: A better Stylish Smartphone Faraday Box

With the release of WikiLeak’s “Year Zero” information on the CIA’s capabilities, you might be forgiven if you’re worried about your privacy.

Of course, those capabilities were always there, whether you knew about them or not.

Still, it’s a bit annoying to think that some bozo is remotely activating your smartphone’s mic to spy on your extremely dramatic dinnertime conversations.

You could buy some overly expensive “Faraday Bag” to stick your phone in when you’re not using it, but who wants an ugly black overpriced lunch bag?

Instead, just make your own Faraday Box. It’s stylish, it’s hip, and it only takes about 10 minutes to make!

What’s with this “Faraday” thing?

Michael Faraday was an English scientist who contributed some seriously cool discoveries to the study of electromagnetism.

A Faraday cage (or bag, or box) is a shield or some kind of enclosure that blocks electromagnetic fields – like radio waves from your phone, WiFi, Bluetooth, etc.

No waves in or out means no spying!

Faraday Bags

Yessir, right now for the low-low price of $58, you could have your very own professional quality law enforcement-approved extremely modern “Rugged Forensic Faraday Bag”:

But yeah, these things are basically just foil-lined pieces of fabric.

Why do I want one?

Well, if you’d like to be safe, you could remove your phone’s battery when you’re not using it. But not all phones have removable batteries these days.

When you put your phone in a Faraday Bag or Box, the radio emissions to and from the device are blocked. Okay – technically, these signals are hugely attenuated, so effectively the phone is blocked from sending or receiving anything to anyone.

Maybe we should call it the “Anti-Alphabet Soup Box”. Nah, kinda wordy…

Is Scottie’s Faraday Box really hip and stylish?

Judge for yourself:

Forget ugly black sacks. This puppy was supposedly hand-crafted in India! Which probably means it was mass-produced in China (with an Indian present) for high-volume sales on Amazon. 😉

How to build your very own Sassy Faraday Box

Step 1:

You need to either find a nice box that your smartphone(s) fit inside, or buy one on Amazon. Like this one (click image to view on Amazon):

If you need a larger box for more gizmos, try the Store Indya Wooden Trinket Box.

Right. While you’re on Amazon, grab some aluminum HVAC tape, like this stuff:

Step 2:

Once your goodies arrive, you just need to line the inside of your fancy box with this conductive aluminum tape.

To see how to apply the tape, check out the pics below of my box.

Note the lip on the box. The aluminum tape should be stuck down and folded over on the outside of the lip. For the larger areas like the bottom of the box, just overlap multiple strips.

Note also the corners and inside edges of the box: the tape should overlap so there are no gaps. Be careful not to tear the aluminum tape when you’re sticking it down!

Here you can see better how the strips of aluminum tape are folded over the lip. When the cover is closed, the metal tape inside the lid will overlap the lip on the outside, ensuring there are no gaps in the conductive metal “cage”.

Here we have the lid. The tape doesn’t have to go to the very inside edges of the lid, as long as there is enough tape on the outside lip edges so that there are no gaps in the metal once the box is closed.

Here you can see the front of the box just as the lid is closing. I’m not worried about the lack of tape on the corner of the lip because the aluminum tape on the inside of the lid covers it nicely.

Once the aluminum tape is stuck down nicely, it’s less likely to tear. But for added durability, I cut a small piece of plexiglass and stuck some felt feet on the bottom. This adds a touch of whimsy, and it prevents any sharp edges on my phone from scraping up the tape on the bottom of the box.

All done! I spent about 10 minutes lining my box with aluminum tape. Pretty easy! Now I just close the lid, and…

Does it actually work?

Yes. I took my 4G phone to the place where I usually get the strongest signal. I then plopped it inside the box, and closed the lid.

After a few minutes, I opened the box, and presto! No signal.

I repeated the experiment several times in this and other locations, just to be sure. The Faraday Box also blocks WiFi and Bluetooth signals.

Did I mention that it’s also quite stylish?

Final tips

If you’re worried about your Smart TV spying on you, you don’t have to get a large Faraday box. Just unplug/disconnect it from your wired/wireless network when you’re done using it.

Also, don’t use WiFi. Just don’t. I know, that’s annoying. But with a wired ethernet network, you automatically make yourself less of a target. Magical waves flying through the air can and will be intercepted, even if they are encrypted.

And as for your smartphone, save some money and build your own Faraday Box… And then the CIA will call you a “paranoid bastard” too!

Which is funny… If you’re spying on me, by definition I’m not paranoid for thinking you’re spying on me, because you ARE spying on me.

Well, at least the CIA and NSA are good at hacking things even if their brains don’t function very well when it comes to things like logic and reason. 😛

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13 thoughts on “Build your own stylish signal blocking smartphone box in ten minutes

  • 10 March 2017 at 19:10

    Thanks Scottie, easy to follow instructions and a snazzy design, I will definitely be trying this out.

  • 14 March 2017 at 06:19

    Nice box, although you might want to connect the foil on the lid to the foil in the base, or you will have built a capacitor, and you may get a kick out of it.

    • 14 March 2017 at 12:15

      Lid + box are connected when the box is closed due to the overlap. The aluminum tape I used doesn’t have any kind of coating, and is nicely conductive (checked with a DMM just to be sure).

  • 27 December 2017 at 00:45

    Thank you for this article and video. I was wondering…

    If I were to run a power cable through a small hole to charge the phone, and the cable has ferrite chokes both inside and outside the box, will the phone still be protected? Isn’t this is how SCIFS allow power inside.

    How well would this box work, as you’ve designed it, against an EMP or a Carrington Event (CME)?

    • 27 December 2017 at 14:05

      For power into the box, I’m really not sure how to do that properly. Any gap in the foil means a place for RF to potentially leak out. At high frequencies like for cell phones, that gap doesn’t have to be very big at all. Here, I was primarily concerned with when my phone is “off”, and when I can’t remove the battery, how do I totally isolate it from any and all waves flying around out there?

      As for something like an EMP, as far as I know that’s a whole other ball of wax. Usually, nested faraday cages are recommended with a relatively thick layer of insulation between each foil layer. And the thicker the foil, the better… Blocking a large EM pulse and blocking very low-power RF emissions are different animals. As far as I know, anyway!

    • 23 October 2019 at 10:00

      You could also buy a big power bank and put that in the box removing any risk of a leak.

  • 21 September 2018 at 20:15

    Put the phone in a foil potato chip or aluminized mylar electronics bag before putting it the box for additional protection.

  • 30 September 2018 at 05:22

    This is kinda redundant, beter thing is to build a noise-box , with a mixture of white and pink noise..

  • 18 March 2019 at 08:02

    When you take the phone out of the box, will it work right away?

    Also, will this block headphones outside the box or speakers from connecting to a phone that is in the box??


  • 6 June 2020 at 10:24


    I’m trying to construct a Faraday cage/shield with which I can block EM signals to and from my hacked laptop, whilst also at the same time being able to use the hacked laptop.

    Was thinking of using a mylar thermal tent as they are very cheap, and because mylar is supposed to be good for EM shielding. Could use aluminium tape to tape up the gaps whilst inside the tent. but then could perhaps cause air circulation problems. Do you have any thoughts about this, as well as on the overall subject of using the hacked laptop?


    Mark Fernandes

    P. S. You may be interested in the recent free wiki book on inexpensive end-user computer security that I’ve created, hosted at https://en.wikibooks.org/wiki/End-user_Computer_Security

  • 23 February 2021 at 13:17

    Hello Scottie, once inside a faraday cage box, will the phone search for a signal and drain the battery?

    • 23 February 2021 at 16:38

      Yup. That’s why you should turn it off before putting it in the box. 🙂


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