Ok,
Here very simple examples for "cap ends", (results surface only)
Useful or not`?, possible in conjunction with other Commands

(StraightSnapON, ObjectSnapON)
TrimCommand__Add trim points__Done__select new edges__use BlendCommand "value 0"
(observe seam, there must trimpoint get set, other trimpoint opposite)


TrimCommand__Add trim points (4points added)__Done__select new edges__use NetworkCommand (observe seam)


two trimed edges + line__LoftCommand used



SweepCommand used__edges is profil__middle line is rail (ShowPointsON)

__SweepOption End: PointyEnd__after "Done"

__Top most point selected__ moves to middle