Getting the frame lines right on a clear canopy is one of those jobs where one slip costs you the whole part, and doing it on both the inner and outer faces doubles the risk. That is the problem MM Scale Models takes on here, using nothing fancier than masks cut from ordinary masking tape.
The method starts on the inside, with strips of masking tape pressed over the canopy facets. Frame outlines are traced with a mechanical pencil, then the tape moves to a self-healing gridded cutting mat, where a scalpel blade guided by a steel ruler cuts along the traced lines. The finished masks are repositioned onto the matching internal window panels. On curved sections, liquid masking fluid is applied with a fine wire probe instead. The exterior windows then go through the same routine of pencil tracing, cutting and liquid masking.
Painting is done with an airbrush in two passes: green acrylic over the whole piece for the interior, followed by a dark grey coat that goes on the outer surface only. That two-sided approach stands out to me, since it gives separate control over how each face reads once the model is finished. Both colours look sharp against the clear plastic in my view.
It is not a zero-cleanup process, and that seems worth saying. After every tape and liquid mask layer is lifted off with tweezers with fine tips plus a scalpel, minor overspray still has to be scraped away with a toothpick. The completed canopy ends up displayed on a rotating mirror, and the frames come out looking crisp. One thing I would still like to know is how the tape masks behave on very tight compound curves, since that case is not covered.
Project by MM Scale Models. Watch it on their YouTube channel: