This sounds like it's a modeling question, actually. I'll move this to the correct forum
Looks like the red line is not a smooth line. That might be problematic. You can do 3d fit splines, or control point splines.
@jeffescott wrote:Looks like the red line is not a smooth line. That might be problematic.
The red curve looks like hand drawn sketch in image editing software to illustrate design intent.
Can your Attach *.f3d file of your “solution”?