We want to make a split mould from a cedar strip canoe, but I was wondering what the best material is to do this job. I know that the most use poleyster/CSM but I saw also molds made from epoxy/fiberglass. In epoxy/fiberglass I guess you have a lighter mould, but how how many layers do you need to make them stiff enough with fiberglass? Is a tooling gelcoat necessary or can I start with epoxy on the waxed plug?  What are the advantages/disadvantages of both systems?

What are you making the finished part from?  Typically unless you have a specific reason to not use polyester moulds - eg using epoxy for the part, or a need for low shrinkage, then most will still use fairly traditional polyester based mould systems.  A good all round method would be to use a vinylester based gel and filled tooling resin so you can use the mould with any resin system and its shrinkage is reduced. Epoxy can make good moulds but is considerably more expensive and not necessary for many applications. A good all round system would be our Uni-Mould Complete Mould Making Kit

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

The Uni-Mould would be fine for that.  Just be aware flax fibres swell up when wetted out with resin so some form of vacuum processing is beneficial.  Ideally Resin Infusion as it will keep the resin consumption down. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant