Matt Groening used to trace his comic strip, Life in Hell, using his sliding glass door. He’d do the pencil sketch, then tape it up on the door and ink the final strip while standing. The fact that he lived in sunny Los Angeles probably helped; if I had to wait for a sunny day in Portland I’d never get any inking done. And forget using a brush, unless you like the Pollock drip method applied to comics.
Another tracing method I’ve recently tried is good old fashioned tracing paper. I’m able to draw in pen on the tracing paper, because when I scan the image it looks the same as if I drew on Bristol board. I only use tracing paper for little drawings or pieces of larger things; drawing an entire comic on tracing paper wouldn’t be pretty. I press too hard when I draw; the paper would get torn. And the originals would get crinkled up and lost.
In my high school art class, there was a huge light box that allowed you to put your sketch on a shelf that you could crank up and down. You could make the sketch bigger or smaller to fit the final drawing. Because it was in a bright classroom, our art teacher had built black curtains all around the light box. You entered it like a voting booth. I wonder if Matt Groening has one of those in his house now, since he’s got like a billion dollars. I know I would.