Automate the Iteration of Geometry of Built-up Section for PEB Design

Can anyone teach me or point me to useful references about integrating an outside macro/ program that would automate the input of the geometry of built-up sections? Need it for the design of PEB on which most of the structural members are built up and we need to do manual input of the tapered section iteratively. Thanks!

Would like to create my own program almost similar to this : www.youtube.com/watch