MOVPE is more of a self-assembly process than 3D printing, and it has been around for decades. BTW It is worth noting from your link that the silicon is being

MOVPE is more of a self-assembly process than 3D printing, and it has been around for decades. BTW It is worth noting from your link that the silicon is being grown on a GaAs substrate, so to be useful they would have to figure out how to grow the silicon wire on a silicon substrate. (GaAs already has many options for optical devices.)