[Tom]

You are going to use fine line tape this is a product made for that type of work it is a plastic tape that bends and stretches very easily to go around corners and comes off without damage to the surface it also cuts a fine edge when removed, it comes in 1/8, 1/4, 1/2,3/4 and 1 inch widths nice product.once you have the design taped off use a 3M pad to scuff the exposed surface so the new paint will stick paying attention to the edges. then paint it

 

[Tom]

most automotive paint stores carry fine line tape the one I get most often is a 3M product but there are other brands, I do most of my dealings with Sherwin Williams they also carry House of Kolor paint products