I'm with Chad. If you only need 1 off (like the cowl) just carve it from white foam slightly undersize, cover it to protect it from the resin (I use brown paper & PVA (white) glue) glass the outside then remove the foam when cured. Water dissolves the PVA glue.

You will have some filling & sanding to do but for just one part it's the least amount of work. - John