Hello, as others have suggested before it would be good to be able to import geometry from an IFC file:
Here I found an IFC - OBJ converter: http://ifcopenshell.org/ifcconvert.html
It would also be useful to export to IFC some geometry, at least as simple extrusions.
Here’s an example of how to make a wall… which is basically an extruded polyline:
The IFC template is also quite well explained in the example.