Not very high on the excitement scale, but here’s a utility definition to extrude any number of profile shapes along any number of curves.
The curves don’t need to be linear since the definition uses [Sweep1] instead of [Extrude Linear].
Specify an insertion point to determine where the profile is located with respect to the rail curve(s). Rotate the profile around the rail if you need to.
DEFINITION
proExtrude.ghx (Right-click on link and “Save link as…”)