On one hand, Sydney's BioShelter using complex marine-biology-based data algorithms and 3D printed molds to create what are essentially custom condos for oysters. On the other hand, Miami's ReefLine is jump-starting its coral restoration by sinking 22 full-scale concrete cars made from 3D printed molds. Which will sea creatures prefer? We'll have to wait and see if they favor hydrodynamic perfection or the eternal charm of a '98 sedan.