I made this drawing tool with Python Mode for Processing, to let people make their own horizontal patterns.

Identify an existing tool in a piece of “drawing,” “painting,”  or “drafting” software you regularly use. Some examples could include the “paint bucket” or “pencil” tools in Photoshop; the “blend” or “Pen” tools in Illustrator; or the “array path” command in AutoCAD. The tool itself is not extremely important, though it should be a tool that you understand completely in terms of what it does. Before you start, be sure you understand what it requires to function. You should also be able to predict the outcome before you use it. That’s the one of the requisites of any tool: the ability to deploy it in a specific way to achieve some kind of desired outcome. Once you’re ready, your task is to write your own improper version of that tool. Before starting, make sure you have a good working definition of “improper.”