13. The one or more non-transitory computer-readable media of claim 11 , further storing instructions causing performance of: matching the particular key-value expression to a set of default attribute values for the custom product; and causing display of the set of default attribute values for the custom product.
11. One or more non-transitory computer-readable media storing one or more sequences of instructions which, when executed, cause performance of: receiving, from a user that is customizing a custom product, a first attribute value that defines an attribute of the custom product; in response to receiving the first attribute value, generating, based at least in part on the first attribute value and one or more other attributes of the custom product, a particular key-value expression that includes a plurality of key attributes and values; matching the particular key-value expression to a set of one or more render files; based on the set of one or more render files, rendering an image of the custom product.