Engineer to Order (ETO) products are built to customer specifications. The ETO approach to manufacturing is similar to Assemble to Order (ATO). ETO is often an extension to ATO, where a manufacturer can still accept orders which cannot be built from the components used for ATO – but instead of refusing the order, the manufacturer designs and makes additional components.
Other ETO environments are general job-shop operations which offer to build anything a customer has designed. Another important class of ETO is capital equipment such as equipment used in process plants, where design and manufacture of each item is often adjusted for the specific installation.