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It's digital. It's like a signature. Black indicates digital. Blue is real ink on paper. I think it's really interesting.

Also, I like very much the numerous mixed styles in here. He's got your standard sketching, scribbles, and smudging. Versatility knows no bounds.

Yeah, it's good to be versatile.
I just shared the timelapse process of it where I added colors to it.
https://peakd.com/hive-158694/@maxwellmarcusart/qzswaprb

Thank you.
Nop, I used digital brushes called paint tapered, ink pen and medium tip marker.