Journal Article mechanical metamaterials 3D printing 9006-04-6 Arabidopsis thaliana Bioengineering Nylons Plant biomechanics Plant cell walls Plant stiffness Polymers Research Support, Non-U.S. Gov't Review Rubber Stiffness gradients additive manufacturing catalysis color changing composites inverse design iron kirigami lightweight materials negative stiffness programmable inflatables shape shifting snap-through instabilities soft robotics strength stretchable devices