I made this design many videos ago. Its a base for holding an Arduino or CHIPINO module that works well with my book: Arduino - A Beginner's Guide to Programming Electronics. I'm sharing three main chapters here that can help you understand how your 3D Printer works.

Chapter 2 - Flash an External LED (Digital Output Example) Chapter 6 - Sensing a Switch (Digital Input Example) Chapter 7 - Read a Potentiometer (Analog to Digital Converter Example)

Download the file to get the .stl and the free three chapters.