Basing their calculations on the density of a modern warship, they estimate that the first Death Star would have required 1.08×1015 tons of steel. That would use up all the iron in the Earth’s crust, and quite a bit from the Earth’s core, which might not be the most advisable place for a mining operation.
Assuming we could gather and refine all that iron — a process that would take 833,000 years at today’s production rates — the value of the steel at current market prices would be around $852 quadrillion.
That’s 13,000 times the world’s GDP for the steel alone. We’re not even talking weaponry, wiring, and trips to Ikea.
So, rest easy. Even with a sizable loan from a certain Hutt crimelord, there’s no practical possibility that any government in 2012 could construct an operational Death Star.