Hello
I would like to change material factors for steel, but there is no option to do so i the API (that i have found).
Is there an easy way to do so ?
The default values from the Eurocode is not the same for building and bridges.
Hi @Bjornar 
You have to options 
Option 1
Use a simple python component to get access to properties which are not accessible through Grasshopper toolbox. It is really simple
modifyMaterial.gh (56.3 KB)
Option 2
You can manually modify the value within a .struxml and read the new material as shown in the blog post.
It might be that you need to change the Guid of the material otherwise FEM-Design will not accept the new properties
Let me know if you need additional help
Thank you for the quick response Marco!