If we want to recycle materials we would do better if the materials had low bond energies, so rigidity in biological materials then comes from high density of secondary (weak) bonds and / or high second moment of area. We tend to go the other way, preferring high energy bonds necessarily created at higher temperatures. These are then much more difficult to break down. Either route can produce materials capable of self-assembly. But the in vitro generation of self-assembled molecular structures, and ideas about generating the ideal conditions for such self-assembly, are not currently in the mainstream. This implies a number of lines of experimentation for which we currently have the kit but not the people. Such low hanging fruit.