You aren’t REQUIRED to show any code. You can discuss the software design practices that were considered and what it meant to your coding style or program creation. You certainly can include snippets of code to support your discussion which would be a real good idea. The code or snippets can be included in the Appendix to avoid taking up space in the precious 30 pages of Engineering Notebook. Regarding MATLAB/Simulink, you can take a snapshot of the screen and save it as a picture to reference. It doesn’t make sense to show the underlying generated code from a Simulink model. How would you possibly point out “good software design practices” from this generated code?