Painting A Decoartive Design Over A Nitro Finish?

[Ducati]

Let's say you want to paint a design by hand over the finish of a guitar. If the guitar has a nitrocellulose finish, what materials would you choose to paint with?

I am looking to paint a design on top of a guitar without taking off the finish. I may or may not want to add a protective coat over the artwork when it is done.

What materials will have long life and not harm the guitar finish?

[syxxstring]

One shot paints would be my choice desigend for pine stripping and sign work. Your local autobody, sign, or art supply may have them.