Which is the best to use? As I understand it, if I am painting the parts its ok to use epoxy, but if I plan to leave it unfinished, then its best to use polyester. Is this correct? Also, is it recommended to use a gel coat first then the resin or just go straight resin? I want my parts to be as lite as possible. I am trying to make my parts around .040 - .050 thick. I tried making my first panel just as a test run and it came out ok, but when I go to make my parts for real I want to make sure they are the best they can be. Does anyone have any suggestions or tips?

I attached a pic of what I am trying to replicate. You can see what is carbon here. Bascially all the cosmetic panels and hood are what I want to make.