A faraday cage is shielded enclosure made from metallic material that protects against the effects of electromagnetic energy.
Electromagnetic Shields can protect your electronics from exposure to electrostatic discharges produced from an electromagnetic pulse (EMP), solar flares or lightening strikes.
Why is it important to know about faraday cages?
If you can protect your electronics from, let's say, an EMP, you can continue to communicate or receive communications from others while those around you cannot.
Consider the damage from solar flares, too. Solar flares (sometimes also associated with a coronal mass ejection) are capable of extreme damage to modern computerized equipment! You can protect yourself to an extent by keeping a Hand Crank Radio on hand, but it even then, unless your electronic equipment is protected from an electromagnetic pulse, it will be fried! The solution is to have a faraday cage and keep your electronics inside when you anticipate something happening.
Faraday cage material: Electric fields are best conducted by materials that conduct electric current - silver, copper, and aluminum is 60% of copper. Iron/steel is farther down the scale. Aluminum is a good poor man's foil against an EMP; double wrap it to be safe.
The instructions below are from Jed Daniels.
Step one: buy the necessary components.
Here is a list:
Step two: Cut the wood. I cut the 2" x 2" furring strips into four 18" lengths and eight 12" lengths. And the 1" x 2" strip into two 18" lengths and two 12" lengths.
Step three: Screw the frame together. This isn’t rocket science, so I’m not gonna give you detailed instructions on this part. Just remember to drill pilot holes for your screws so you don’t split the wood. Here is the assembled frame.
Step four: Build and attach the lid. I simply screwed the 1" x 2" pieces I had into a square and put them on the frame box with a piano hinge.
Step five: Attach the screen mesh. I will never regret the day I bought my air compressor and pneumatic stapler. I can only imagine the terrible hand cramps had I attempted this with a standard spring loaded stapler. If you don’t have a pneumatic stapler, I highly recommend you at least look into purchasing an electric one. To make sure that everything was tight, I tried to keep staples no more than 2 inches apart (usually about 1 inch, but towards the end I got a little tired and lazy, so the space between increased a littler).
Step six: Attach the ground wire. Attaching the parts was pretty simple.
I cut off the two prongs that get electricity. I wanted it to be perfectly clear that this plug is non-functional, and won’t create an electrified cage (cause that is a completely different project!). [NOTE: This is dangerous! Don't do it. If there are some cables crossed or your ground is wired incorrectly, you could create a lethal situation and die. Get an electrician to get you a dedicated ground wire to use for a project like this. If you kill or seriously injure yourself, don't blame me, I told you not to do this. Seriously, I'm not joking. Don't plug stuff into an outlet that connects to bare metal that you will be touching. That is just stupid.]
Step seven: Time to test! I plugged in the ground, got my laptop and started measuring Wi-Fi signals.
Building instructions provided by Jed Daniels:
As an alternative, if you don't want to make your own, but want something to protect your electronics. This is an awesome Faraday Duffel Bag. It is made of ballistic fabric, so it is extremely sturdy. You can also shield multiple electronics devices at the same time.