I was just wondering if it would be feasible to make molds of a fin i want to make out of styrofoam blocks and then pour epoxy resin in and let it harden. After that I would like to sand it into a decent shape to make a longboard center fin. Is this wishful thinking or do yall think it would work.
As a furniture maker, I have made many high-style and collector board skegs (fins)with various woods. I have done as you suggest with molds, using polyester and casting resins. On some I would foil completely prior to “casting”, others I would cast the wood fin, then foil the full casted piece (about 1/2" thick or so). One of the big problems is bubbling of the resin. I have had no experience glassing, but worked with the advice of a friend with 20 years experience doing surfboards. Since “casting” is a little out of the norm for most surfboard glassers, we found that trying to get the cast to come out crystal clear without any blemishes (my main goal) was difficult. You will of course still have to laminate the skeg for strength with at least 2 layers of 6oz (more?) for strength. Don’t know if your plans for color or foiling, but perhaps someone with experience can shed more light on what your are attempting with foam.