Comment by A_D_E_P_T

I'm working to figure out new auxetic geometries for 3D lattices. The arrowhead is cool and simple, and gyroids are very effective, but I'm trying to discover if there's something simple, printable, and maximally effective. Tough problem. There's no general theory for auxetic lattices, so it's a matter of reasoning from the desired mechanism to find patterns that fit, almost like alchemical trial-and-error.