+xBack in the olden days, we used to wet lay old skool polyester based carbon sheets using a brush/roller applied gelcoat. To avoid visible brush marks, what we used to do is very lightly drag the roller across the surface with a finger stopping it rotating. That was just enough to skim off the brush strokes. A small flat piece of plastic would likely so the same thing. That way, in future, you can remove the problem while the gelcoat is wet leaving you less work to do later on.
Like using a squeegee?
I will give that a try, thanks!