"The Things He Carried"excerpts:
" “It’s allowed,” he said. Medical supplies, such as saline solution for contact-lens cleaning, don’t fall under the TSA’s three-ounce rule.
“What’s allowed?” I asked. “Saline solution, or bottles labeled saline solution?”
“Bottles labeled saline solution. They won’t check what’s in it, trust me.”
They did not check.
“Maybe if you lit it on fire, he’d pay attention,” I said, risking arrest for making a joke at airport security. (Later, Schneier would carry two bottles labeled saline solution—24 ounces in total—through security. An officer asked him why he needed two bottles. “Two eyes,” he said. He was allowed to keep the bottles.)
...
“The whole system is designed to catch stupid terrorists,” Schneier told me. A smart terrorist, he says, won’t try to bring a knife aboard a plane, as I had been doing; he’ll make his own, in the airplane bathroom. Schneier told me the recipe: “Get some steel epoxy glue at a hardware store. It comes in two tubes, one with steel dust and then a hardener. You make the mold by folding a piece of cardboard in two, and then you mix the two tubes together. You can use a metal spoon for the handle. It hardens in 15 minutes.”