Essentially we are running down all of the classical uses of foam and trying to use fungi grown to order as a replacement.<p>Packing materials were tried early on, and while they could get the shape and the strength right, getting the weight competetive proved to be a daunting task. One company whose name I can't recall put out a couple press releases about advances in weight savings with their materials, then quietly disappeared.<p>Like batteries, there are plenty of stationary uses for heavy solutions to the same problems. In fact I'm sort of surprised none of those packing people pivoted to sound or thermal insulation.