In 1964 the US government decided to find out how easy is it to build an a-bomb. They set two physics PhDs the task of designing an atomic bomb with no prior experience or access to classified research. After 30 months they had a design for an implosion type bomb (not the simple cannon type) that military scientists confirmed would work and had about the same yield as the Hiroshima bomb. It turns out that it is complicated enough that a school kid can’t do it but there’s nothing a physics post grad couldn’t handle.