[GOPJ]

note that the GA Tech device was a "water bottle," and Hinrichs' car was found to contain "plastic bottles..." No shrapnel at OU. Might have had a plastic container for the TATP...As thin as 2 liter bottles are now, and as unstable as TATP is fireworks on the outside might be enough...sealed container, cheap, no stink.

Other than no stink, what's the advantage?

[Smokin' Joe]

No metal detector signature, colored bottles may not be obvious enough to be detected visually, cheap, readily available, could be disguised among other bottles filled with chem or bio agents in case lots and used as a dispersal charge, other things might apply...