One more thing.. 

What do you think is the best way of setting up the epoxy inlet , vacuum port and spiral looking at the mold I posted in page 1?
I plan on using infusion resin IN2 slow.

Alright.. I have sold my older Kemppi ac/dc tig welder to get some funds to order some carbon fiber stuff. I still have my newer Kemppi ac/dc tig left so no wurries..

I want to learn this and make alot of stuff in the future so it will be a pretty large order to get all the equipment.. I have some stuff as vacuum bags and some stuff to make wet layups but I need degassing and catchpots etc..

What I am wondering or debating about is what to use as backing material in the layup..
I will use 200g twill as first and last layer but what is a good and economical material in between? I do want a material that will be easy to get in the corners of the mold I posted earlier..
About 1000g total should be enough thickness I think.. What do you think about that looking at the pictures I posted earlier..?

What I am looking at now for adding thickness between the two 200g twill  is ether 3 layers of this 200g second grade twill:
https://www.easycomposites.co.uk/200g-black-stuff-22-twill-3k-carbon-fibre-cloth

or two layers of this 380g twill:
https://www.easycomposites.co.uk/surplus-carbon-fibre-8hs-satin-weave-3k-366g

or 2 layers of this:
https://www.easycomposites.co.uk/surplus-carbon-fibre-8hs-satin-weave-3k-366g

Or maybe two layers of this:
https://www.easycomposites.co.uk/wholesale-offers/Incredible-Discounted-Carbon-Fibre-Biaxial-300g-1m-Wide.html

I never got issues with either delamination nor twisting. And I even made a counter mold for a glass plate. There is not a single mm twist over one metre. Wood works fine too, but it has to be dry, and fully enclosed by glass fibre afterwards, because otherwise it might take up water, and expands

If I can make the mold to last for making more roofs later I think will be nice.. Who knows.. the car can get vandalised or i can sell one if they came out nice.. 

Hanaldo:

Timber.. Is that pices of wood? To me that is what you cut down with a chain saw..

Last time I used the old mold I hade heater fans under the roof mold to give the curing process some heat. I imagine that the sun can make the roof pretty hot during sunny summer days. I guess maybe I got the mold to about 40-50 deg.
So if I do some kind of wooden struckture I dont want it to distort the mold.

If you mean like wood planks I guess I would do a frame with 4" x 1" standing planks and a cross in the middle so you can lay the curved mold with the wood structure on a flat flore. 
Will that be a good way you think?

You don't need a better spray gun, you just need to practise using the one you've got. A top quality spray gun makes the difference in the hands of a top quality spray painter, but if you don't have much experience with spray painting then you wouldn't notice the difference between a job laid down with a $50 gun or a $750 gun.

As oekmont suggested, coremat works ok for building thickness. Personally I prefer not to use it in moulds as it isn't as good as a monolithic laminate, but for a one off it will certainly do the job. Alternatively, pieces of timber bonded or glassed to the back of the mould are a common way to form a rigid backing structure. Timber is a good option because it doesn't shrink like composite resins do, so a well designed timber backing structure will ensure your mould remains dimensionally accurate. A mould made with coremat will twist if it doesn't have the geometry to resist, which your roof doesn't. But again, you're doing this for a one off, so coremat is easier and will do the job. 

If you got access to lantor coremat, this would be a really easy way. Two layers of reinforcement like 450csm, 5mm coremat followed by 2 layers of reinforcement gives a thickness of around 10mm, and is lighter and cheaper than building up thickness just with csm.

Thank you.. Good advice.. 

I do have a air compressor but I only have a cheap paint gun and I have very little experiance of using it at all. But it should be fairly easy to dial in the gun to get a deacent result I guess. 

I need to get a better gun but i am almost up to £2000 of stuff as it is right now..


Back to the mold.. The thing I am worried about are the 90degree corners along all the edges combined of 5 layers of 200g carbon fiber.. I am afraid that the layers will "lock" themself to eachother under vacuum to make it very hard to push the layers in to the corners without bridgeing.. 

Also when making the mold for this big flat roof I need it to be very thick to get some kind of stiffness if I am not useing some kind of braceing..  I would think about 10mm.  Any advice on a good way to brace the molds backside?

Possibly one of the simplest panels you could ever make, theres nothing complex to be scared of there. In response to your original post, I would say don't bother with the spray tack. You will get a much better result without it, and you certainly don't need it for that roof. Rather put your time into watching the EC infusion videos and study how they deal with the bagging so that there is no bridging in the corners.

2k paint is very hit and miss, especially the rattle can stuff as it contains a lot of solvent. If you don't have a compressor and a spray gun though, it may still be your best option. But I would recommend using PVA as your release agent to make the mould. It is much easier to polish a PVA mould surface up to a full gloss than it is to fix alligatoring caused by the gelcoat attacking your paint. 

Finaly got som pictures..



The old mold messed up. The air holes were grinded out so they would fill with body filler but as mentioned before I decided to scrap it and do a new mold.:





The car without roof but with the stock skeleton left to glue the carbon fiber roof to.:


The new roof I got..:


The new roof had a few dimples in it and I need to smooth them out with body filler.. My plan was to use a 2k rattle spray can for the last finish and wet sand the transition and polish it up to a nice glossy finish. Then I read in a post on here that that kind of paint can make the surface of the mold of the roof bad. 
Any suggestions what to use?