To make a material light enough and strong enough at the same time, besides enhancing the material's intrinsic properties, one can also adjust the material's structure.
In this regard, the bones of birds serve as an excellent reference.
Birds have evolved to the extreme for the purpose of flight. Everything from their streamlined shape and feather arrangement to their muscles, internal organs, and bones have been specially adapted.
For example, bird bones are as hollow as possible internally while still having support structures to ensure the entire bone is lightweight and has sufficient strength.
In the original world, humans learned this technique from studying birds and applied it to the construction of aircraft.
Beyond applying this technology to the overall structural design of airplanes, humans developed a new material based on this principle, called foam metal.
