As search engines continue their trend of considering your search term just a suggestion, I can't pull it up, but there's also a case where a high school physics class decided to try to design one and also came adequately close.
The hard thing that is actually the stopper is the enrichment of the relevant materials. The other hard part is getting the best possible yield; there's huge variances in what you get from the same amount of fuel depending on how well you can put it together before it blows itself apart, but that's not a stopper for a terrorist group. Getting to Hiroshima levels is apparently not that difficult, as evidence by the fact it was done so many decades ago.
Delivery is another major challenge, but I'll consider that separate from the task of creating one at all.
1964, Physics PhD who knew nothing about nuclear physics designs a bomb: https://www.theguardian.com/world/2003/jun/24/usa.science
Physics junior in the mid-1970s designs a device good enough to impress Freeman Dyson: https://en.wikipedia.org/wiki/John_Aristotle_Phillips#%22A-B...
As search engines continue their trend of considering your search term just a suggestion, I can't pull it up, but there's also a case where a high school physics class decided to try to design one and also came adequately close.
The hard thing that is actually the stopper is the enrichment of the relevant materials. The other hard part is getting the best possible yield; there's huge variances in what you get from the same amount of fuel depending on how well you can put it together before it blows itself apart, but that's not a stopper for a terrorist group. Getting to Hiroshima levels is apparently not that difficult, as evidence by the fact it was done so many decades ago.
Delivery is another major challenge, but I'll consider that separate from the task of creating one at all.