Lost wax or lost foam process for hollow parts

I would like to know if someone has any experience with the use of a lost wax or lost foam processes to obtain a hollow CARBON FIBRE part, (it is 260 mm long x 220 wide x 40 tall).
I know they can be used to produce fiberglass parts, but I am interested in the compatibility of those processes with carbon fibre prepreg and with curing temperatures of around 80ºC.
I would specialy appreciate it if someone knew anything about some hard foam that coud be machined to provide a male mold and then be disolved after the curing process.

It’s not a hard foam but a paste that sets like plaster… And you wash out the plug after the part is made.

Something like this:-

http://www.acmtucson.com/products/water-soluble-molds-and-tooling.html

Also, Google: “water soluble moulds”

And do a search on here as there are other threads too.

Yes astute is absolutely correct