hey man try this get a mini hot glue gun. and any dollar store has glue sticks. heat that gluegun up and then take a popsickle stick and put a dab of glue on the end of it let about a second to pass then dab the decal/undesired area to paint. Then before the glue hardeness all the way use your fingernail while the glue is still warm to decrease the area untill it's just what you don't want paint on. I also used a fiber glass detail pin to knock off that clear coat around these gluemasked areas and a fine grit paper (grey) to knock off the panels. USE RUBBER GLOVES WHEN USING THE FIBERGLASS DETAIL PEN OR ELSE AND WORK OVER A DROP CLOTH. some water in a cup or wet rag will also be good. I'm making a flat black GTR with a driverside police dome cleardome and clear Led, But the Led is Blue when lit.
Hope yours turns out well.
P.S. exacto knives are your friend for .0001 detail!!!!