I would like to create a solid model element by using ‘solid by extrusion along’ function, but the path line is from the reference file which I cannot pick it. See below image. Is there any way that I can create a new line by snapping the reference line? or can I copy this single curved line into my model?
In the ‘Solid by Extrusion Along’ tool setting, tick the ‘Keep Path’ box, this will allow you to use referenced element. In the case of this tool ticking ‘Keep Profile’ will retain the profile that you extrude along the path. See below image.
This should resolve your problem.