The number-loons at Pennsylvania’s Lehigh University economics blog have done some number crunching in an attempt to figure out the logistics and financial cost of actually building a 140km diameter steel Death Star. They figure the Earth contains enough iron for 2 billion of the things.
Now the bad news.
Scaling up to the Death Star, this is about 1.08×1015 tonnes of steel. 1 with fifteen zeros.
But, before you go off to start building your apocalyptic weapon, do bear in mind two things. Firstly, the two billion death stars is mostly from the Earth’s core which we would all really rather you didn’t remove. And secondly, at today’s rate of steel production (1.3 billion tonnes annually), it would take 833,315 years to produce enough steel to begin work. So once someone notices what you’re up to, you have to fend them off for 800 millennia before you have a chance to fight back. In context, it takes under an hour to get the steel for (the British aircraft carrier) HMS Illustrious.
Oh, and the cost of the steel alone? At 2012 prices, about $852,000,000,000,000,000. Or roughly 13,000 times the world’s GDP.
The second Death Star was 900km in diameter. So that’s even less of a runner.