I confess to also being interested in a moldless one off process but yet is still relatively constrained to a design.

An approach I had in mind was building a strongback and form setup as usual but using that hard yellow foam for the forms. Then gluing a series of layers of string netting over the forms. Then series of thin layeres of spray foam (urethane) into the netting to get the shape. Sand down to the yellow forms and netting in order to get close to final shape. Then use a fairing board. Add glass, sand smooth, cut along shear, pop off, join up and paddle.

I think I could make that work. An idea anyway.

-mike