I know a man who back in 1993 worked at the old (now closed) National Fertilizer Development Center in Muscle Shoals Alabama when the Oklahoma bombing took place. The primary ingredient in the bomb was ammonium nitrate which is a primary ingredient in fertilizer.

He and is colleagues were tasked to see if a way could be found to make ammonium nitrate in bulk that could not be used to create a bomb.

To find out how the OK bombers made the bomb they had to use a copy of Playboy magazine for reference because a reporter for Playboy outdid the FBI and ATF and discovered how the bomb was made.

I don't think they succeed because of the Beriut blast a couple of year ago.