Dave,
The PM you and I exchanged got me interested in making some molds of the dirtbike parts off of my YZ450F. I started the process for making a mold of the exhaust heat shield. I took some photos last night and I will document the entire process as well as making a carbon part from the mold. So keep an eye on this thread, I'm sure it'll help you out.

okay.. here's the exhaust shield the I prepped with a flange using hot melt glue and playing cards covered in vinyl. The entire thing has been waxed multiple times and sprayed with PVA(poly vinyl alcohol) which will form a thin layer of vinyl to insure the plug doesn't stick in the mold.

I then mix up an epoxy surface coat that I blend using secret ingredients and brush it on the plug about 5 mil thick. You can also use polyesther tooling gelcoat depending on if you're making an esther based mold or epoxy based. I only make epoxy based molds.

after the epoxy surface coat b stages(cured enough where you can touch it without anything coming off on your finger), you brush on epoxy resin and lay a few layers of fiberglass working it in so that everything is fully saturated. Only do a few layers at a time as the heat created by too many layers of epoxy and fiberglass can damage the mold. You should always vacuum bag epoxy molds as it's almost impossible to get all the air bubbles out of the laminate without using vacuum. You don't have to worry about vacuum bagging if you're making an esther based mold as you would be using CSM instead of fiberglass cloth. You repeat this process until you build up a thickness that is equivalent to 3 times the thickness of the parts you will be producing. I often use coremat between laminations to build up thickness and strength. I forgot to take a photo of this process but here's a photo of the mold after I finish laminating and popped it from the plug.