I really don't have much idea where the designs "come from." I'm not even sure what exactly triggered my desire to draw intricate little patterns, when I was a young boy.
I've tried to rationalize that it was just a form of "doodling" that took shape, over the years. My doodling became intricate because I spent a lot of time alone... and since we traveled all the time, things I chose to do (like hobbies) had to be very small, light and movable. But those answers just feel like excuses and rationalizations.
Oddly enough, I have never owned a microscope... but macro photography became a hobby of mine, soon after I got my first "serious" camera. Some people are fascinated by landscapes and sunsets; some are brilliant at photographing people-- my thing was always to explore the "innerscapes" of everyday objects... sharing a point of view few of us ever pause to consider... or even see.
I once met someone else-- a girl in one of my 8th or 9th grade classes-- who drew very similar patterns. We never really interacted, but there was something comforting about seeing another person who seemed to "see" something in a similar way. Other than that, we were nothing alike, however. I was awkward and geeky and quiet; she was pretty, outgoing and "popular."
I discovered at an early age that drawing intricate patterns had no bearing on artistic ability or expression. My mom saw my "doodles" and figured I would be able to draw amazingly intricate art-- but I was miserable at drawing, painting and other forms of art, feeling lucky to scrape by with a C-, most of the time. I could never make anything I looked at look anything like realism, on paper.