Engineer to Order (ETO) production approach, where after an order is received, a part of or the whole design is done. It is also described as Build to Order (BTO) and sometimes referred to as Make to Order (MTO). See descriptions.
BTO is the oldest style of order fulfillment and is the most appropriate approach used for highly customized or low volume products. This approach is most common for large construction projects and one-off products, such as Formula 1 cars.