Speaking of painting technique.
Years ago, when I was sign painting, I did some small murals, street rods and things in signs. Never used a mask for any of this. But I did do some comic super hero panels, masked and spray, mask and spray with rattle cans of paint. Then did the "inking" or line work with a brush in the styles of the artist, like Buscema and Wrightson.
Having said that, I was a a county fair and there was a bloke doing shirts with airbrush. He was doing little things, like '57 Chevy's on the pocket. But what was interesting is he was using a business card as a moving mask. So to make a straight thin line he would hold the card against the shirt, moving it along the long side with the airbrush close and a very fine light spray he could made a very sharp line. if he moved the brush off a bit the line would have a sharp edge and soft overspray edge. He would bend the card to make a curve, and fold it to make a corner. I went back to the shop and tried it all and it worked a treat.......
Just sayin..... nothing ventured, nothing gained.
*Haven't thought of this for years..... this was back in the 80's maybe.