Hi Andy,
Welcome to the forum.
I just had a go at the guitar finish with sunburst paint. Attached is a scene (KeyShot 10) and screenshot.
I do think you will need to deep dive into the Material Graph to get the appearance just right and flexible, so that it works with minimal adjustments on different models.
To achieve the sunburst paint, the takeaway is to use an Occlusion (or Curvature) texture as an opacity map for the black color on the sides. Unlike most other procedural textures, the Occlusion texture is raytraced, and therefore allows you to "highlight" or color areas of the model with e.g. tight curvature, as would be the case on the sides of a guitar. The Occlusion texture can be used as opacity for a paint Label or as a alpha mask in a Color Composite node, depending on the requirements of the material. In the example, I went with the latter, and combined the black color on the sides with a procedural wood texture through a Color Composite node.
For the clear coat, I would suggest adding a black shiny Plastic material with high IOR (e.g. 2.5) as a Label, and use a dark grey color as opacity. A Color Adjust node (without inputs) is ideal to get a solid color for the opacity.
I tried to give the nodes sensible names, so hopefully the Material Graph setup makes sense.
I hope this helps.
Dries
