I'm porting a set of cylinder heads for my 5VZ-FE rebuild. I'll have a thread or two in the future on my progress and the finished project once completed. My plan for this thread is to share my resources that I learned this from and the photographs of the molds of the stock unchanged ports.
I originally learned about head porting from my Dad. He's ASE certified and builds FAST smallblock Ford V8's. He's ported his own cylinder heads in his garage for all the years that I remember growing up.
I read about port molds in David Vizzard's book "How to Port & Flow Test Cylinder Heads" (ISBN 1934709646) - my Dad loaned me a copy (thanks Dad!). However, it wasn't until I came across an article on diyporting.com that clearly outlined the port mold creation process and provided a list of material that is easy to obtain: http://www.diyporting.com/molds.html
To state it simply, the idea of creating port molds is to see the form of the ports in order to get a better idea of how they can be reshaped so that power increases can be obtained by reshaping the port. My port modification will be limited to removing material - I don't plan on doing any radical port reshaping or adding material.
The supplies I used to make these molds include:
1) A set of cylinder heads (this should be obvious
2) RTV silicone - any parts store should have this
3) A paint brush. Something cheap will suffice. Don't plan on using it for anything else because the silicone will probably ruin it.
4) A release agent. I used WD40 in a pinch and I didn't have great results. I will be using an alternative release agent in the future. See the previously mentioned diyporting.com article for a better release agent.
The first two pictures are of the 5VZ passenger-side cylinder head that the molds were made from, and the silicone RTV and paint brush I used.