https://www.youtube.com/watch?v=XeeSsmsm9h0
lets say im making a mold exactly like this tutorial shows,but i want to make a pattern out from this mold with vacuum infusion.should i do anything different?the ionly thing im imagining to do is applying extra layers of coopling coat and some layers of chopped strand mat.have i thought it right?

I have got a mould just like that (an airbox, 3 piece mould), and I made several parts with resin infusion. I didn't bag the whole mould, just the inside, like it was a one piece mould. The split flanges have sealing channels, which I prepare with tacky tape. The channels are inside of the bolting points (and there are a lot of bolts. When everything is put together, there are two points, where the sealing channel (and therefore the tacky tape) exits the mould. During the final bagging, I have to  take up this points wich the tacky tape / bagging film corner. After that, the bag should be absolutely tight, and the resin doesn't flow anywhere it isn't supposed to be.
I can't take a picture of the mould, because it is a customer project.
split mould infusion is absolutely an advanced process.