Collect all categories in a project

Is there a way to select All of the Elements in the entire Project? I have tried feeding individual categories into List.Create as you have shown. I am concerned that this method is prone to user error if someone forgets to add all of the categories in the project. Additionally I noticed that there are many solutions that involve Python coding. I am new to Dynamo so I am difficulty understanding the posts that use long strings of Python code.


I am creating a script that calculates the volume of all of the Concrete in the entire building. I successfully created a script that can calculate the volume of all the elements on a specific floor. Instead of using “All Elements at Level” I’d like my script to be based on all Elements in the Project. Is it possible to do this without first learning Python coding?
Below is my functioning script, based on materials on a given level: