I would like to crete Trajectory Rib feature for open geometry - at this moment it is only possible create this feature for closed boundary - see discusion here
I'd add to this that it would be helpful to be able to designate endpoints as termination points.
Currently all open ends are either trimmed or extended to the outer part walls. In some cases the user may want the rib to terminate inside the part or there may not be an outside wall, as in the discussion above. Being able to to designate an open endpoint as the end of the rib would allow both of these use cases.