Just trying to find out if there's any reason why you cannot do a hand layup in a silicone mould (in this case epoxy / carbon fibre).

All I tend to see in searches are silicone moulds being used to cast solid resins or plasters.

Silicone would be the perfect material to make a mould from the object I want to duplicate (although, there are no complex curves or fine details)  and ideally I would use the mould to make both a plaster 'buck' for vac forming and also do a carbon fibre hand layup.