According to the official Zentangle website, "Anything is Possible One Stroke at a Time. At first glance, a Zentangle creation can seem intricate and complicated. But, when you learn how it is done, you realize how simple it is . . . sort of like learning the secret behind a magic trick. Then, when you create a piece of Zentangle art, you realize how fun and engrossing the process itself is." Here are some examples from the website:
I encourage you to take a look at the Zentangle website or the class instructor, Diane Knauff's, website.