gt4 air intakes

The original fibreglass intake channels which fit to the side ports (and then connect to the rubber bellows and the airbox) are unavailable and are missing from one my gt4's. I do have a pattern available as they are on my other gt4. Any ideas what substance I can use to get a mould from the original ones without damaging them? I guess I can then make a fibreglass copy from the mould.