How to model precise parts in the bim-model e.g. a curtainwall-facade

Mas

1. get the profile (almost .dwg)
2. convert to .dxf (2007ASCII) (libredwg, ODA-dwg converter)
3. import in blender
4. delete lose parts
5. convert to mesh
6. "limited desolve" (10° works almost for me)
7. fill it
8. shove the inner face up a bit and seperate it ("P")
9. select the bigger face "TAB" to editmode
10. Select in the Outliner the innerface with "Ctrl" and jump to topview "numpad7"
11. "mesh-knife-project" (generates the most precise and useful face for profiledef)
12. delete inner face -jump to objectmode- and delete the 2nd seperated object
13. scale it and apply scale "shift+A
14. add the face as abitrary profile (work out the details e.g. radius in profileedit)
15. create beam/colum out of it, add instances
16. add boreholes and cutouts as voids, fase at the ends as halfspces
    IMO this workflow generates parts that are precise and useable in other software for further workflows.