[alarie]

We make 1 time molds all the time in our shop, using whatever wood type products you can (such as thin ply or hardboard) to get the shapes you want. Put some ribs on the back (outside) once you are satisfied with the shape. You can then radius the corners at the top with bondo and fill any nail holes as well. We then spray the tool with gelcoat and give it a quick sand, and then use a spray on release agent like PVA (water based) to make sure it the molded part releases. You can then spray gelcoat right onto the PVA and mold away. You will have to do a bit of final sanding on the gel once the part is done, as the PVA will have a small amount of texture that will print on the gel surface.

Works great and you do not have to use any expensive boat bulding type materials (core cel or balsa) to make your mold.

Good luck,
Peter