Designing a scientific plotting package is a daunting task—the needs to cover are extremely diverse. On one hand, ideally, creating any kind of figure should be possible with a minimal amount of coding and fiddling around. On the other, we want to be able to customize any aspect of a graphic. Those two goals are diametrically opposed. matplotlib offers a rare balance between the two goals. In this chapter, we will explore ways to modify fundamental aspects of the stock figures, such as changing the coordinate system used.