Your lines are the law
The drawing is read as the structure layer. Nothing is straightened, shifted or improved on your behalf.
Drawings
A pencil drawing, photographed.
Hand sketches, elevations and bare CAD views come back as photographic images with the lines you drew treated as the structure.
Rough is fine
A photograph of a sketch on paper works. It does not need to be a clean export.
One drawing, several finishes
Show a client the same scheme in three material palettes without redrawing anything.