The correct answer is all of the above. However, there are degrees of customization. The most basic form of customization is designing an installation with cabinets that will be built for your job specifically, not pulled from inventory. Even entry level cabinetry will be made to order and the design will be specific to your project. There will be limitations and/or pricing premiums for ordering outside the standard offerings. An example would be ordering a 23″ cabinet to avoid using a 21″ standard size cabinet with a 2″ filler in the same space. The 23″ cabinet is considered “custom” in terms of it’s size. An entry level manufacturer will charge a premium, as much as an additional 50% of the price of the cabinet, to “custom” size the cabinet. As you move up the manufacturer hierarchy (stock, entry level, semi-custom, custom) these limitations and premiums drop away. For example, Plain and Fancy does not charge for exact sizing. A 23″ cabinet is ordered as a 24″ and the exact is requested, no additional premiums. If you take the example to the next level, by not charging sizing premiums when entry level manufacturers do, a higher end supplier will be a better value.