custom-built vs custom-made

custom-built and custom-made both are nouns.

Word	Noun	Adjective	Verb	Adverb
custom-built	Yes	Yes	No	No
custom-made	Yes	Yes	No	No

As nouns, custom-built and custom-made are synonyms defined as:

custom-built and custom-made: an item made to the customer's specifications

custom-built (noun)	custom-made (noun)
an item made to the customer's specifications	an item made to the customer's specifications

custom-built (adjective)	custom-made (adjective)
built for a particular individual	made according to the specifications of an individual