Building-attached surface ghosts become real when covered with another surface

1. Place a vehicle depot ghost
2. Paint over the concrete surface in front of the garage with a different surface
3. Fill in the surface.
4. Remove the surface.
5. Concrete surface now shows visible, not a ghost.
6. Delete the vehicle depot ghost, the concrete surface remains. However, it cannot be interacted with.
7. Save + reload, now the concrete surface can be interacted with, and can be deleted for concrete.

updated two images but don't see a way to update

Are you conjuring concrete out of thin air?

Yup, that’s correct! Though without the save/reload, it only partially exists.

I suppose you could do that for a massive area. But if does it require you to have the materials to cover it (Steel or Concrete?)

Yes, you do need the materials to cover it in a real surface. You’ll get it back (or some, maybe, on other difficulties?), but it would certainly not be a very quick way to generate concrete.

This issue still exists in version 4.1.

Final state is some flooring that cannot be affected until the next save/reload.