Somebody can explain me how? Ty!
This looks like a scan or photo of a hand-rendered illustration to me.
If you are specifically talking about the hard-lined / wavy / linear pattern, that can be done with Illustrator’s pen and ellipse tools.
If you’re looking for a “push this button to get this effect” solution, there isn’t one that I know of.
Not looking for a “push this button to get this effect”. Just want to know how to do this hard-lined/wavy/linear pattern, I love it!
Illustrator’s shape tools, pen tools, pathfinder palette, and appearance palette are your friends.
practice practice practice.
There is no how. There is only do.