Ah, "guncotton". Back in the very politically incorrect mid-1960s, one of the experiments in my freshman chemistry class at VMI was making guncotton. I have long since forgotton the exact formula, but it was really astounding how easy it was (as long as one was careful with the acids). Apparently, guncotton was historically the staple of cadet "bombs" which were hurled into the courtyard on random nights, and, I'll attest, it was easier to make guncotton in the Chem labs than it was to obtain the preferred substitute M-80s.
It would be easy enough to stuff a teddybear with guncotton and have some poor unsuspecting kid carry it on board, I suspect.
Just when I have gotten up the courage to make airline reservations again, here comes the specter of exploding teddybears. Sigh.