Help understanding how to work with prepreg

Hi everyone,

I'm just trying to educate myself about composite construction
techniques, and I'm a little confused on the process of using prepreg
materials in an autoclave. Could someone who has done this help me
understand the process?

Assuming I have prepreg cloth and access to a large autoclave and I
want to make a part, say a seat for lack of a better example, what
would I use for core material, and how do I keep it from getting
crushed in the autoclave? Typical foam that I am familiar with will
melt under the 250F curing temperatures, and it seems that a core like
Nomex honeycomb will be crushed when the pressure is applied. I can
imagine how to do a mold, but it seems like any core material will
come out a molten, flattened mess.

Can someone help out a novice understand how this is done? What do the
big boys do when they want to make a high temperature part? I'm having
trouble visulizing how this actually works.

Thanks for educating me. This is just for my own enjoyment and
edification, but alot of people I've asked have the same question.

Chris