You can build the Wood Ducks with only a couple of sawhorses and no forms. That being said, I use the temporary forms and permanent bulkheads to determine the shape of the bottom and make two forms that match them out of scrap 1/4" plywood or anything else I've got laying around in the shop and screw them to the sawhorses. You can tape some foam or cloth on the tops of the forms, or go to your big box store and buy a piece of foam pipe insulation, the kind with a slit cut down the middle, and tape that on them. 
 

George K

Posts attached to the sawhorses with a nylon webbing sling worked for me on my WD12. They automagically adapt to the exact shape of the hull and need no padding. They're not as rigid as what George describes, though. I wasn't bothered by that, but some builders might be.

Laszlo

   I built a pair of workstands from the design on page 72 of Nick Schade's book, The Strip Built Kayak.  CLC has a similar design here: Sawhorses and Slings (clcboats.com).  This type of stand can be used to build either S&G or strip designs.  I mounted them on locking casters so I can role it around as needed.