Sometimes you need to mask of areas differently if you don’t manage by “just” applying strips of masking tape around the area you want to have masked. Here is a different approach, you apply the stripes all over the area and then use a scalpel (a sharp one so be careful!) to cut out the area you want to paint. Here the area are the 2 rear air scoops in the rear area of the Porsche.
Detail view of the masked area ...
... and the cut out area afterwards
As you can see, my scalpel was not sharp enough, so the edges do look more ripped than cut. For me that means … do it again. Anyway, here is also a complete view of the car with the samples …
The masking again ...
... and from the other side.