custom fiberglass

[bug man nrg]

yes you can use wood
but you must seal it first wiith a filler and sand it down then prime it be for coating it with mold wax so it not stick to your mold

[NO_H2O]

I have also seen a thin plastic like film that comes on a roll used for a parting media. It was a pink color and would allow you to skip the sanding and prime/paint step.

[justdubbin]

I've never tried it, it's something I have thought about but I don't have anywhere to try it out.
Anyway I have looked about previously on the net and heres just one of the pages about mould making I have found.

Hope it helps.