The Nth Country Project, recently declassified, was designed by the military in the 60's to find out how easy it is for non-experts to design an atomic bomb. They found out that it was pretty easy. Two physicists with recent PhD's and no atomic expertise were asked to design an atomic bomb with no access to any classified information:

The quest to discover whether an amateur was up to the task presented the US Army with the profoundly bizarre challenge of trying to find people with exactly the right lack of qualifications, recalls Bob Selden, who eventually became the other half of the two-man project. (Another early participant, David Pipkorn, soon left.) Both men had physics PhDs - the hypothetical Nth country would have access to those, it was assumed - but they had no nuclear expertise, let alone access to secret research... Eventually, towards the end of 1966, two and a half years after they began, they were finished. "We produced a short document that described precisely, in engineering terms, what we proposed to build and what materials were involved," says Selden. "The whole works, in great detail, so that this thing could have been made by Joe's Machine Shop downtown." ...Finally, after a valedictory presentation at Livermore attended by a grumpy General Edward Teller, they were pulled aside by a senior researcher, Jim Frank. "Jim said, 'I bet you guys want to know how it turned out,'" Dobson recalls. "We said yes. And he told us that if it had been constructed, it would have made a pretty impressive bang." How impressive, they wanted to know. "On the same order of magnitude as Hiroshima," Frank replied. [Guardian]