I did a class 12 months ago, drawing an outline of a turtle with coral, rocks and seaweeds. We drew the outline on on plain white fabric, made a sandwich with backing and binding, then proceeded to fill all the background with zentangles, using the quilting foot and feed dogs down. Didn't think I made a very good job of it, only got it half finished, and haven't had the urge to get back to it. Takes a long time, though I did enjoy.