raygreenwood wrote:
Or....possibly a mulched paperboard, then a spray gelcoat to make it smooth and waterproof. That would be very close to stock. Ray
Yeh - I am inclined to think of a papiermaché (thanks, Albert ) but with an epoxy as a binder - vacuumed onto your former. A polyethylene parting film and release film - with the upper film 'bagging' the former. A coat or two of paint to protect from the UV - better than new.
But then I am not too familiar with what the part looks like, so maybe I should shut up!
Wallace...you are just about on the mark. I would build the mould as for metal casting...plaster. Then make a "porrige" of mulched paper, rag fiber and epoxy. For release, I use micro-powdered Urethane release spray powder. Its invisible. Sprays on dry like "cooking spray". Its great for very fine detail. The real thing to test for though....is wether it holds up to heat. Even the epoxy will have some heat distortion.
This parts is about 4' long and has compound curves and vent holes cut in it. We'll see. Ray
) but with an epoxy as a binder - vacuumed onto your former. A polyethylene parting film and release film - with the upper film 'bagging' the former. A coat or two of paint to protect from the UV - better than new. 
