AJ, Wood isn't often used in Foundry Molds where molten metals are cast - due to the propensity of being burned in the process. Each successive casting with a mold would yield a slightly different part(s). For small runs, you may wish to investigate "sand molds".
Molds for carbon-fiber reinforced epoxies or fiberglas can be and often are made of wood. I am an inventor and have numerous molds in use for these products and we use wooden-reinforced translucent grade silicone molds, or in some cases with extremely simple profiles we'll use UHMW PE molds or mold liners.
In the past, I've owned manufacturing of specific-application ceramic molding - it may be that for your foundry work a high-strength and very durable ceramic mold may be workable. Ceramics that are cast from "slip" are cast-into molds made of Plaster of Paris.
Plaster of Paris cannot handle high temperatures, typically - but making positive to negative molding and changing materials as one goes is one approach.
Native Americans (and quite likely Aboriginese) made bridges across huge ravines, rivers, gorges, etc. beginning with thread shot with bow and arrow. From the opposite side, a coworker would tie-on a string and the shooter would pull-back the thread, followed by the string, the shooter would remove the thread and tie-on a thicker string, bla, bla, bla. Eventually a heavy "rope" would be stretched across the ravine - using several workers on each side to pull the increasingly heavier thicknesses of ropes.
This same principle can be used in many things having to do with manufacturing - it just requires someone to "think creatively" and use progressing materials along the way. Every big man-made production begins with something smaller than the tiniest seed - an idea. For one to be a successful inventor, one must be willing to be a successful failure. To me a successful failure is when something logical is attempted and then fails. Success often is when something is learned through failure of a logical process and then experience becomes wider. And don't ever be chicken to try something logical just because a friend said it cannot be done - but has no good reason. Just always be mindful of safety procedures along the way.
Otis Guillebeau from Auburn, Georgia USA
OPG3 Tweak everything!