Since the most Jello you could bring through security would be a one-quart zip-lock bag, I'm assuming you're planning on buying said Jello after you've cleared the TSA checkpoint? If you plan on stuffing your duffle bag with Jello and don't think you'll be able to find it at the airport, might I suggest finding a large number of friends to travel with you. Each of them could bring a one-quart zip-lock bag of Jello through the checkpoint while you bring your empty duffle bag. When you get past security, all the Jello could be consilidate into your suitcase. Hopefully you won't have a problem getting it in the overhead. [/silliness]