The original model of the National Archives Vault that stores the US Constitution, Declaration of Independence, and Bill of Rights. Originally, the vault was a special Mosler Safe Company build, but was replaced in 2000 by a Diebold vault. Mosler was the legendary company that built the Fort Knox vaults and the Manhattan Project blast doors.
And here we have the vault model being demonstrated in 1954. From the left, that's vice-president Richard Nixon, Ohio senator John W. Bricker, and Mosler president Ed Mosler Jr. Displaying this model got Mosler the contract. The model was later donated to the US government, was lost for decades, and was recently discovered gathering dust in the National Archives building basement, and still functioning.
Previously: Abraham Lincoln's homemade tool - photos and patent