Interchangeable parts were, in a sense, the beginning of the modern machine era. The idea that one part can replace another one while preserving the overall structure is very powerful, and thoroughly embodied in Jekyll. Our projects so far have substituted the default components of a theme with new parts, and more precisely, web technologies that served as perfect replacements. One interchangeable part freely replaced another, without any fundamental changes to Jekyll, and we obtained a new functionality or feature. What happens, though, when you open the hood and look inside? In this chapter, we are going to open Jekyll, look inside, and extend the functionalities that it offers. We will be customizing the feature set that Jekyll offers by adding plug-ins. We start by discussing the role Ruby plays in the making of Jekyll and how to install Ruby offline for your own use. We play with it briefly and use it to create a skeleton Jekyll project. In this chapter, we use a different code-hosting platform called Bitbucket to host the code and show that the implementation of Git across various platforms remains the same. We also go through the workflow of continuous integration and compiling Jekyll in the cloud to include the plug-ins. After the compilation, we discuss the concept of secure keys and how to automate the build process using Codeship to push the code to Bitbucket and Rake, which is a build tool for Ruby. We are not only opening Jekyll to look inside, but also opening a design studio using a Jekyll theme and the plug-ins as add-ons for the various tasks a design studio needs to accomplish.