Thanks 5KinKP60 thats exactly the kind of info I was looking for. The manifold is for a 3TGTE turbo engine. I actually have a friend who is building a light aircraft from carbon fibre and he will be helping me make the manifold. I can get 1m square sheets of carbon fibre for AU$70 so the cost wont be huge. I have discussed the making of this manifold with him and this is how we will make it. 1) Design manifold shape and size. 2) make metal templates of the plenum ends 3) attach templates to high density foam 4) hot wire cut the foam betweem the metal plates to form a mould 5) lay the fibre and vacuum bag it 6) dissolve the foam away