Background section 

At the present time, the "background" section cites unspecified interviews with the media, according to which, Ahmed claimed to "take apart a clock and rebuild it inside a pencil case."

The sentence is taken verbatim from the NPR article. However, it links to a Dallas News article, which says no such thing, to a Dallas News interview, which also does not contain this statement, and mentions a WFAA interview, which I've been unable to find. I've checked four different interviews with Ahmed and he does not explicitly describe it as a rebuilt clock in any of them.

If such an interview exists and the statement was not an interpolation by NPR, it would be nice to have a direct link, a quote and a date.

The problem with the statement is that it provides inadequate background for the rest of the article. When the story broke on 9/15, the device was consistently described by the media as "a homemade clock" or "an invention".  The fact that it was a reassembled commercial clock was mentioned in passing by a WFAA article (which quoted Irving police) on 9/16 but otherwise mostly ignored. It only went "viral", so to speak, when Dawkins waded into the controversy on 9/20 and his comments got picked up by the conservative media.

Much of the immediate reaction, from Obama's tweet and Zuckerberg's invitation to Dawkins' lashing out, seems inexplicable if the device in question was acknowledged to be a rebuilt commercial clock from day 1, but makes sense if the device was initially assumed by everyone to be a genuine homemade clock.