“I have a code that generates a list of cross-sections based on certain criteria. The issue is that when setting up the model, one must assign a cross-section to each column. The type of cross-section chosen will therefore restrict the column to only be able to select that type from the criteria list. Is it possible to set any cross-section as input for all columns, and then when FEM-design runs, it utilizes the given list of possible steel cross-sections to select the appropriate cross-section?”
Hi @larsToppe
Yes, it is possible 
The main idea is to create a custom section pool with the section that you would like to use for the optimisation.
- Define your pool
Make sure that the section belongs to the same “TypeName” - Assign a section that belongs to a pool to your beam
- Autodesign will only use the sections that belongs to the pool
Have a look at the example below
OptimiseCustomPool.gh (74.5 KB)
it is a known bug 
Can you deconstruct the surface and rebuild it?
Try to use Deconstruct.Brep, straighten the outer curve making sure that they are “Line” and it should work
I tried to do as you said, but it still does not work. Any idea what else I can change?
I would like to upload the file here, but get the messeage that new users can not upload files?
interesting.
@larsToppe Do you mind sharing a screenshot that shows the error from Discourse?
Hi @larsToppe
Have a look at a little workaround to make your workflow working.
I hope it helps
sectionDeconstruct.gh (51.0 KB)
It worked, Thank you