They start with a scribble of random lines. Then you create a creature out of them. I am no pro at this. These are crude and beginning sketches that need to be refined. I might refine them or continue to practice his exercise. It is really fun and I implore you to try it if you like concept art.
I like these a lot. I have a similar creation style where I start with some random doodle and then I make a pictograph out of it. It’s not as skillful as what you’re doing, but I enjoy putting all my thoughts and feelings together like this.
This is “Server, Client, Internet”
This is “The Sins of Man”