A tin foil hat is a piece of headgear made from one or more sheets of tin foil, aluminium foil or similar material. People wear the hats in the belief that they act to shield the brain from such influences as electromagnetic fields, or against alien interference, mind control and mind reading.
The idea of wearing a tin foil hat for protection from such threats has become a popular stereotype and term of derision. The phrase serves as a byword for paranoia and is often used to characterize conspiracy theorists.
Of course, just because you're paranoid doesn't mean they aren't out to get you. This is serious work.
Some proponents of a tin foil hat are concerned about the NSA transmitting commands to them. This is clearly nonsense of the highest order. Everyone knows that the NSA only reads your thoughts - it is the CIA that sends commands.The example tin foil hats shown in the Wikipedia article a crude, improvised affairs - the state of the art is evolving.
"Any advice on a proper tinfoil hat? If I use a colander, do I need an airspace between layers of foil still or does the colander suffice?"
Air space is undesireable. Start with lead foil as the first layer. Then at least 3 layers of aluminum. Depends on your risk level. I used 12.
Now, what most don't understand is that it is a good idea to generate an electromagnetic field around the hat. It's like a deflector shield.
You should install on the handles for 8 D-cells or, for longer duration, left and right hip packs for lantern batteries. Tie your packs together then wrap copper connected to the batteries around the hat.
[bobn note: if you connect the batteries so that the current can flow directly across the colander by itself, you will get very hot batteries, or a very hot colander, or both, in a hurry. Don't do this. The current must flow in series thru the colander and then the 12" nail electromagnet noted below.]
Attach a lead to the end of the wrap at the top of the hat and attach it to the leads of an electromagnet. Get some electromagnet copper and a 12" nail. Wrap a bunch of coils of wire around the 12" nail and then attach the leads to the power supply.
I used an entire spool of the thin electromagnet copper. But the strength of the electromagnetic field your trying to achieve is again based on you personal risk profile. The more coils you have, the more frequently you need to change the batteries.
This had obvious issues to which I responded here:
The more coils you have, the more frequently you need to change the batteries.
Sorry, my BSEE says yer wrong. More coils of the same wire increases the resistance to flow of current, increasing the battery life.
But the real problem is that using just batteries only creates a static field - the CIA has known how to penetrate that for years - believe me, I know! You need an oscillator running at a randomly varying frequency, driving the coil thru a hi-power amplifier to have any effect.
I hope that some of you have found this useful. No, really, you don't have to thank me.
(Note: Misean's site is here. He is one of those FreeBSD freaks. I, in contrast, am a linux-head. )