I don't know how familiar you guys are with Zentangle, but it's a cool drawing style/technique that allows you to do pretty much what you want. There's websites and books dedicated to it, but in a nutshell it's using patterns to create a design. I teach this as a lesson for my students: we draw the outline of an animal and put designs inside the body. I have to say, they come out pretty cool!
I often do these as a warm up or to clear my mind. This drawing I did while the kids were working. No grand plan- just having fun.
Sharpies on 9"x12" drawing paper
Art © Nick Mockoviak