Hi Michael:

Thanks for your answer and for the link that really did not solve anything for me because the purpose of this project is not to manufacture the guitar on CNC machines.
It is only to use the guitar, in a virtual background stage for a video, this guitar and many other modeled objects I made them in 3Dmax, but they are not well done, and I am making all the objects made in 3Dmax in MOI that everything is a lot easier and also helps me to learn to model with NURBS which is fascinating.
I attach some examples modeled in MOI and the link of a video of what I use them for.

https://youtu.be/2HPfriGAU4M

In the image of the Steinway B-211 piano I have pending to solve the red seat of the padded stool, I will post this problem here when I solve this one.