how to model guitar neck in Rhino

Hello, do you want to model a triangular one (stratocaster style, with all 6 keys lined up) or a rectangular one (acoustic guitar style, 3 keys on each side)?

Anyway, try to set up your lines first as if you see it on wireframe, then sweep the surface along the lines that form the edges. Model a simple shape first, then complicate it by adding other bodies or making cuts.

Hello, I made this image, https://www.dropbox.com/s/6eplhwzd3zzw74n/gneck.PNG. It will help you understand how to build the surfaces you need. The thickest black lines represent the lines you would have to draw and from which you will need to build surfaces from - either by sweeping or selecting 4 edges. Each color area represents a different surface. Lighter lines are guides to understand the geometry and how surfaces bend. Hope it is useful!