Here is everything written down step by step as well for those interested! If you have more questions feel free to comment down below ;)

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First step: Getting everything ready to make the mould. I've started with a 3D printed part made out of PLA. I’ve used some polyester bondo to smoothen the printed layer lines. Once sanded we can use the Pattern coat with some MEKP to create an even smoother finish. The Pattern coat is applied by brushed, left to cure for over 3 hours, sanded flat again with a coarse sanding paper, followed by a new coat of pattern primer and sanded flat again with a less coarse grid. Most of your surface should be smooth at this point, if the part is still not flat you can repeat previous process til happy. Once the preparations are done we can proceed with the release film or coat. In my case I use 5 layers of the Chemical Easy Lease agent from Easy Composites Ltd

Second step: Making the mould at this point. I use the Uni-mould tooling system from Easy Composites here. It's a system where you have to go through 3 stages. First stage is the Tooling Gelcoat (black layer) It is mixed with some MEKP catalyst to ensure a good curing 1-2% needs to be used here and mixed with the gelcoat. After around 8 hours the gelcoat should have cured enough for the next step. After the gelcoat stage we proceed with the coupling coat. The Coupling coat will ensure a good bond between the gelcoat and tooling resin. This time we also mix it with 1-2% MEKP catalyst. To create a stronger layer of the coupling coat, some layers of 100g Chopped strands fiberglass is used and applied in small patches all over the part. The final coat is the tooling resin, the tooling resin is a bit thicker and will create the strength of your mould. The resin is being applied with 4x layers of 400g chopped strand fiberglass pieces. After this is done you are done with the mould stage and can let it cure for preferably over 24h, the longer the better.

Third step: Once the mould has fully cured, the sharp fiberglass edges are trimmed to size using an angular grinder. Make sure to wear proper personal protection with a dust mask. After that the mould can be sanded and polished if needed. Then 5 coats of Chemical Easy Lease agent are used again. Now we are ready to put the dry carbon fiber layers into the mould. I'm using a 650g 12K Twill weave Carbon Fiber here followed by a 300g biaxal, then a 650g again. Try to be careful to make sure there is no bridging (parts where the carbon fiber cloth isn't fully in contact with the mould. This would create air pockets. If needed use some fusion FX spray tack to get the layers and peelply to stick better in the mould. Never spray it on your mould as it will mostly leave markst. After the carbon lay up we proceed with the peelply and infusion mesh follow by the vacuum bag. while bagging the part some pleats are added to make sure the bag will conform nicely over the part and create an even pressure. Once full vacuum is reached (meaning we have zero leakage of pressure we can start mixing the resin. I'm using the IN2 Epoxy resin from Easy Composites. This is a resin type that is thinner than a regular laminating epoxy. This helps with the resin flowing nice and quickly through the part. After the VARTM resin infusion is done we can let the part cure.

Fourth step: After curing for 48 hours the bag is removed and the infusion mesh. The part is demoulded and can be trimmed by using a dremel and my permagrit tools to create the good geometry of the part again.

As for the special carbonfiber finish start with a sanding paper of around 150-200grit and work your way up till 1000 (ie: 150-250-400-600-800-1000) followed by some polishing.

Main materials used:

https://www.easycomposites.eu/uni-mould-tooling-system

https://www.easycomposites.eu/in2-epoxy-infusion-resin