Yes, it is only done using a 3D sketch, but you should not
have any problems, I have done it many times. I mainly have had
circular parts but I just did an experiment with an ellipse and
spline extrusion and had no problem either.
yeah. using the 3d sketch it lets you relate the point. since
you are not on a flat plane you need to tell the point where it
needs to lie. i just use other surfaces or planes to fully define
it. works perfectly. i have also used the plane normal to a point
on the surface. also works great. just depends on what you are
trying to accomplish
SA