drwg 3-D tubes w/ radii using extrude & pathcurve

Now I have 2002, and am not sure if this is possible yet.  I tried it with
R13, 14, if not others.


Trying to draw (commonly manufactured) tubes (hollow) like an exhaust
system.

Something will not compute.  Maybe something about multiple planes.  Can't
remember if at the pedit stage, or extrude, or how to work around.


I'm trying:
Drawing contiguous straight lines joined at ends in multiple planes, then
adding radii, join them all together with Pedit, to use as a pathcurve.
Then drawing circle(s) perpendicular at the end, and polyline as a pathcurve
to extrude.


I'd love to get to the bottom of this.