Comment by fc417fc802

A sufficiently detailed render won't require a designer to figure out the materials. Any (reasonably competent) contractor can take a sufficiently detailed render with him to the store and find matching products. At least assuming the thing in the render actually exists.

He can also send back a picture of the real product for approval. I think the primary difference here is the level of involvement. A quick consult and then the professional "makes it all work" versus hands on design with the client figuring out all the details for himself.