https://phys.org/news/2018-06-lab-d-carbon-blocks-applications.html

The technique detailed in Advanced Materials is an extension of groundbreaking work by the Tour lab that produced the first laser-induced graphene (LIG) in 2014 by heating inexpensive polyimide plastic sheets with a laser.

The laser burns halfway through the plastic and turns the top into interconnected flakes of 2-D carbon that remain attached to the bottom half. LIG can be made in macroscale patterns at room temperature.