The surface detail of an artefact is sometimes not decided by the design but by the maker. Especially for artefacts that are made by hand. Often these surface details are only decided as the maker makes the artefact. Some of these surface details cannot be made by machines.
Think of polish, texture, sanding, or some other tactile surface quality. This is an important part of our experience of an artefact. It’s what we see with our eyes, and feel with our hands.
Good craft often pays attention to the quality of the surface layer of the artefact.