Brian's workshops have the advantage of getting a nice, custom sized SOF finished within 8 days, but you do have to pay for the privilege, approximately $1200. This in sharp contrast to my $200 SOF, after 8 long years of building (or actually non-building).
There are other faster and cheaper ways.
I just read an articles about two paddlers who do it their way. It works for them, and they're having great time doing it. Father and son Ben and Daniel Glick started out wanting a fishing kayak. A little design work, $25, PVC piping, duck tape, some plastic sheeting, 5 hours of construction, and they were done. They wrote an article called "American Ingenuity" detailing the story of this build in the online magazine, Duck Works, a magazine about home built boats and their adventures.
Well, Ben and Daniel didn't stop there. Next, they decided to sign up to race in this years Albuquerque’s “Great Race down the Rio Grande”. They'd need to build a double. This new kayak, was also a PVC, duct tape skin-on-frame, using two old bed sheets and some exterior latex paint. They won in the home made division. And they wrote another article in Duck Works Magazine about this newer kayak "Two Seat PVC and Duct Tape Kayak".