"Design sketches" refer to rough drawings or drafts created by designers to visualize and plan the appearance, structure, or details of a product, building, or artwork before it is finalized. Full definition
The company has also released a few design sketches of the 2014 A8. (indianautosblog.com)
In addition, every game has new achievements and development extras (such as design documents, character design sketches, audio and video commentary). (shacknews.com)
He hired a vice president of manufacturing before there was even a basic design sketch. (inc.com)