[Oorang]

How to Build A Faraday Cage

[Myrddin]

I'm familiar with how they are built. I have to work inside them from time to time. In that case, the intent is to keep signals inside, not to exclude them from outside. We use Tempest devices inside with fiber optic networks to limit radiation. The Tempest version of a Sun SPARC II was running almost $20,000 in 1991. Certified and tested shielding drastically increases the cost of a device.