I don't know if anyone's tried this before but I came across it almost by accident while trying to figure out how to do the best job on a Sherman's turret.
I'd filled the cap and was thinking of a way to replace the cast texture that sanding had removed.
Then it hit me

I found an old brush and cut the bristles down very short, and then spread 'Tipp-ex' correcting fluid over the area and stippled it with the brush. Worked like a charm.
A very quick and easy fix.
Just thought I'd share.
Tom