Phil there is not an easy method. It requires patience and attention to detail.
I use car lining tape the blue one which is very adhesive but does not leave any residue.
It is the one car sprayers use for the decoration of cars. It can be stretched around corners.
Comes in three thickness's. Best I found is a quarter of an inch.
I always cut a new strip down the centre of the tape so that I have a sharp virgin edge.
Place on the alignment of the framework. Cut each end on the frame alignment. Any mark
is covered. Lay down the cross pieces and these can over lap the first piece as the
adhesive quality is great.
Look on the underside of the plastic cockpit which gives a great clue as to whether you are
on the alignment of the frames. When you have finished all the frame edges mask with tape
all the exposed bits.
Burnish down the tape on the frame edges. I use a finger nail.
Then I coat the plastic exposed frames with very thin coat of Vallejo Matt varnish to, hopefully, seal
any edges not sealed.Also gives a good surface for the paint.
Airbrush a thin first coat. Thin as any area not sealed will be with out great seepage. Then a full coat
Then leave 48 hours. Then with a sharp preferably American Razor Blade very carefully score
along the edge of the tape lines. American Blade as it is thin and very sharp.
Then very slowly remove the tape pulling to the side rather than along the line. If there is an seepage
cut on the line. Carefully scratch with a wooden toothpick away the paint seepage. With IPA use a
small pointed cotton bud to remove carefully any residue.
Not easy. But the first thing you see on a model is the cockpit cover. If it looks rough then the model
does not look good.
Should it go wrong remove all paint with IPA and start again. Done that. Next time it will be near perfect
If possible use magnification to fix the tape and get it aligned accurately.
Laurie