Collaborating with bioengineers at Rice University, generative design studio Nervous System creates complex blood vessel networks using custom software and 3D-printed sugar. “After printing, these sugar templates are cast in a mixture of living cells and gel,” they write on their blog. “When the gel has set, the sugar is dissolved, leaving the intricate branching network that serves as blood vessels for the living cells.” According to their paper in Nature, the cells can be kept alive for two weeks.