Years ago I lived in NYC and belonged to an art group associated with Grace Church. There was a member of the group that did guerilla mosaics. He’d go into the subway at night and measure the holes where tiles had been broken and create art to fill the spaces. Then he’d slip back into the station and glue/grout the artwork in place. I loved the idea, and seeing his art around the City. This looks like something he would do, though much more advanced in technique.