I never thought about it being a "zen" thing but I've done this sort of doodling since I was in middle school and come to think of it, I'd do it when I was nervous, upset, or overwhelmed. ( I usually 'doodle' when I'm bored)
Zentangle DIY ink bubbles tutorial by on deviantART . great inspiration for when I'm drawing and can't figure out what pattern I want to use next. Which happens more often than I'd like to admit. -- what a great idea!