No intersection between target and split tool

[Anonymous]

I have a car model that I’ve been working on that I need help with.  I have attached the .fd3 file.  When you open it up, you will see the body of the car.  It is a hollow body with a horizonal plane at its roof.  What I’m trying to do is split the body at the offset plan near its roofline.  I then would like to give it some thickness so I can print it out on a 3d printer. 

When I try to split the body I keep getting the message, “No intersection between target and split tool.”  I assume it’s because it’s not a solid body?  Also, if I somehow do get this body split, can I convert from B-rep to T-spline in order to thicken it?

Thanks for any help or direction you can provide.  If I can figure out what direction to take with this part, I’ll be able to do the rest of the car also.

[TrippyLighting]

Fusion 360 is the wrong tool to work with .stl meshes the way you are intending to.

Use Autodesk Meshmixer.

This thread has a good explanation of why working with a .stl might not provide you with the results you're looking for.

[Anonymous]

Thanks @TrippyLighting .  I have Meshmixer but don’t have much experience with it.  I’ll dive into it today and see what I can come up with.  Thanks again for the suggestion.