As an artist I'm always looking for ways to push my work to be more interesting. I've found that some of my most engaging work comes from imposing creative constraints on myself. To this end, I had a concept for an app I would definitely use: "a drawing prompt with variables"
I started with a very basic wire-frame. I wanted 3 or four text items that were randomized independent of one another.
For the next step I wanted to determine what the variables would be. I settled on four variables. Two would be related to the subject matter and the other two would be related to the drawing process.
With the variables in place, I then Started to give the wireframe design a more finished look.