The Origami hull is a hull formed by folding steel into the shape of a hull. The hull plates are first butt welded to form a two large flat plates. Each of the two larger plates will be formed into one half of the hull from bow to stern. To form each side, darts are cut into the plate and the gaps pulled together, bending the plate into it's three dimensional shape. When both sides of the hull are completed they are brought together and welded down the keel.
Here is an example of an Origami Boat pattern for a single chine hull. You can download and print the large image of the pattern, then cut out the pieces and tape it together to see how the process works.
See "Paul's 65ft Origami" for an example of how a large origami hull is built.
On Alex Christie's web site, Origamiboats: The Art of Frameless Steel Boatbuilding, you can find more information and purchase a video and book that covers the origami building process in detail. You can also join the Yahoo group; Origamiboats as well as a FaceBook group Origamiboats -- Frameless Steel Yachts. You can also download a self extracting (zip) compressed file of all of the messages on the Yahoo group between it's creation and Jan of 2010: Yahoo_Origamboat_Archive_Feb2000-Jan2010.exe. Thanks to Ben Okopnik for putting that together. And Ben keeps an updated, online searchable archive is here: http://okopnik.com/origami.