Interestingly there seems to be some precedent of terrorists converting seemingly innocent carry on items into bombs.
http://en.wikipedia.org/wiki/Philipp...nes_Flight_434
“US prosecutors said the device was a "Mark II" "microbomb" constructed using
Casio digital watches as described in Phase I of Operation Bojinka of which this was a test. On Flight 434, Yousef used one tenth of the explosive power he planned to use on eleven U.S. airliners in January of 1995. The bomb was designed to slip through airport security checks undetected. The explosive used was liquid nitroglycerin, which was disguised as a bottle of
contact lens fluid. The wires he used were hidden in the heel of his shoe. At that time, metal detectors used in airports did not go down far enough to detect anything there.”