Essentially, you´re making a mold out of fiberglass. You´ll need fiberglass cloth and resin.. you mix some resins like two part epoxys, some you simply pour from a container. It´s messy, hazardous stuff, and you´ll want gloves, mask and goggles when handling it.
The vasoline is to lubricate the mold so that you can remove it from the metal hood, and later to remove the new fiberglass hood from the mold... otherwise the resin will bond with the paint, metal or cured fiberglass.
Instead of filling an entire 3d mold, you can simply lay down layers of the fabric into the top half of the mold, pour in some resin, spread it around, pressing the fabric into the mold so that it´s smooth, strait and runs corner to corner. Then use a kevlar/fiberglass weave to do just the framework from the bottom mold. When you´re done with that you can join the two peices using a little more fiberglass and resin to patch them together.
<- check this site out for some more info
There are lots of different techniques for creating composite parts, and it´s interesting to learn about why certain techniques are used for certain applications. For instance, many carbon fiber products are heated in an enclave (a pressurized oven) to cure the resin. The entire chassis of the McLaren F1 was built using peices of pre-impregnated carbon fiber which already has the resin in it. The cut peices of fabric get clamped together to form components, which are then baked in the enclave for several hours. No mess.
BTW, carbon fiber will cost you about $50/yard. If you decide to put a top layer of carbon fiber cloth on the top of your fiberglass hood for show you´ll end up spending $150 on the cloth alone... but you can still come away cheaper than buying one.. assuming you get it right the first time ;-)