Better data means faster, cheaper design work
Much of the time in a CAD project often goes on working out what applies: which dimensions are critical, how the part is fitted and what it has to withstand. With clear data we can start designing straight away, and you get a firmer price in the quote.
Start with the guide how to measure a part if you have a physical part, or with from idea to product if you are developing something new. If the part is to be made by a workshop, the guides on tolerances and fits and drawings for the workshop help you get comparable quotes.