The Reconstruction Finance Corporation (RFC) was established during the Hoover administration with the primary objective of providing liquidity to, and restoring confidence in the banking system. The banking system experienced extensive pressure during the economic contraction of 1929-1933.
Typical materials used for electromagnetic shielding include sheet metal, metal screen, and metal foam. Any holes in the shield or mesh must be significantly smaller than the wavelength of the radiation that is being kept out, or the enclosure will not effectively approximate an unbroken conducting surface.
Wood, plaster, cinder blocks, and glass don't interfere much, but brick, stone, and water (like a giant fish tank) can block a Wi-Fi signal more. The materials that really block Wi-Fi signals are ceramic, concrete, metal, and mirrors, which reflect visible light and radio waves alike (. Wi-Fi Versus Your Walls.