Just to be clear, blending is what you do to adjacent panels. You paint the new panel with the best color match and then you blend adjacent panels by painting the parts of the panel closest to the newly painted panel and blend so the further away you get, the more of the original adjacent panels paint is visible. You then reclear the entire adjacent panel.
There is no blending with bumpers, mirrors, spoilers, or other external attachments. Insurance industry standard is to only blend adjacent body panel of body panels being repaired.
A good touch up guy that does two stage urethane paint can paint your skull cap for $50 but if you go that route and it isn't someone you've used and trusted in the past, you must have them show you that they're using real two part epoxy and not a single stage that will just come off with any solvent.