Estes Semi-Scale Saturn V, Kit #K-39, Part 23, Silver Fairing Paint

I used Scotch tape masks.

Scotch tape isn't very flexible - so the only way to get the curved line is to set down a piece of tape, then draw an arc with a wide point Sharpie. Wipe off the excess ink with a paper towel.

Cut a smooth arc thru the middle of the ink line.

Here I'm lifting the masking strip off my cutting glass.

On the left, the Scotch tape mask is in place for the silver spray.

On the right, the rest of the body is masked off.

Seal the tape edge with a Q-tip.

It's softer than a fingernail.

Here's the silver paint after the tape was pulled.

I got some good, sharp lines.