Hello, at the moment I prefer to brush gelcoats or pattern coats as I don't have the proper equipment to spray.
Despite the quality of the brush and some thinning, I always end up with brush strokes so a lot of high and low spots.
What is your recommended tool to flatten out the brush strokes?
Besides manual sanding, I am looking into orbital and roto-orbital sanders but not sure what works best or if exist better tools for the job.
Any feedback would be greatly appreciated!

Back 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. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant