Boeing says it's created the lightest metal ever, a microlattice material which it describes as 99.99% air.

Weight savings are crucially important in aircraft manufacturing, since a lighter aircraft requires less fuel, which is airlines' largest operating expense.

The Boeing 787 Dreamliner was a breakthrough commercial jet because it used light-weight composite carbon fiber material, rather than aluminum, to generate the best fuel efficiency in its class.

The microlattice looks like a sponge or a mesh, and is simultaneously flexible and very strong, according to Boeing. Should it become widely used, Boeing (BA) said the material could help airlines save huge amounts of money.

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Boeing describes the new microlattice as an "open cellular polymer structure." The main use of the material would be structural components, such as sidewall or floor panels of commercial jets.

The material was jointly developed by HRL Laboratories, a joint venture between Boeing and General Motors (GM), in collaboration with Cal Tech and UC Irvine. The microlattice weighs only about one tenth as much as carbon fiber, and is actually slightly lighter than air itself, said Bill Carter, the director of the Sensors and Materials Laboratory at HRL.

It will likely first be used on space rockets that Boeing plans to build in about five years, and it should make its way into commercial planes about five years after that, said Carter. He said the cost of manufacturing will have to come down a little more before it is economically feasible to use on cars.