Reminds me of an idea I had for lighter than air packing material. It was going to be something like over-sized bubble wrap filled with helium, or balloons you'd insert into the spaces and inflate with a helium canister. Seems a great idea at first, but then you do the maths, and think about the materials. Unfortunately the weight savings are likely to be so minimal they're unlikely to save on postage costs, and even if they did reduce postage they're likely to be outweighed by the cost of materials. Plus you later find out that lots of other people have had the same idea and posted on the internet about it.