This is a parametric plug panel, allowing you to attach a set of panel-mounted plugs. It includes some ribs for added strength, and it's fully "inside-out" parametric, with the overall size driven by the sizes and distances you choose for the details. It prints out the total dimensions to the output window when rendered.

Open in Customizer, or edit the file directly. The code file contains detailed comments. Choose some values in the "User-defined values" section, render, and print. You may need to run the output through netfabb.