I have two pieces in different planes (e.g. a disc and a metal support with a hole for the cable pass) that are in assembly of parts that I would like to connect them by a straight inclined metal cable. I tried by schematizing this with a 3d sketch line that connects the two parts and then extrude it, it doesn't work, nothing happens. Then, by using inserted a new part in assembly and also with the creation of an inclined plane using the faces of the two parts in question, I ended up having a kind of tube connecting the two pieces but I can't constrain it properly and in addition the created plane encounters reference problems.
In fact, I want to draw a cable with a kind of knot at the end that is inserted into a hole and then I connect this cable with the other piece.
Since it is an assembly, your second proposal seems the most suitable: create a "Cable" part by extrusion and/or revolution according to its section and ends, insert it into the assembly, and constrain its position with respect to the other two elements (disc and support). Either by defining conjugated shapes on the cable and the two parts (spherical spans) with a coaxiality constraint, or more simply by using sketch points with a coincidence constraint.
Since I don't have a 2016 version, I can only offer you images of this superb suspended record...
Indeed I forgot to send you an image. The image I managed to make unfortunately is not too clear, but at least it gives you an idea, I hope, of what I want to do.
