To construct or assemble something in accordance with specific parameters (usually from a buyer). A noun or pronoun can be used between "build" and "to." The client must be rich if he wants us to build the boat to order!

Built, constructed, or assembled to meet one's custom measurements or needs; very well suited to someone's personal needs or desires. Hyphenated if used as a modifier before a noun. It's a nice change of piece getting a suit that's built to order—it looks great, and it fits like a dream! After weeks of searching, I finally found a job that was built to order for me. They specialize in built-to-order cars for wealthy automotive enthusiasts.