Any thoughts to the above?

Imagine I’m creating some linear geometry, like a trough concentrator. I’d like to be able to optimize some of the geometry as defined in the x-z plane, but this geometry is just extruded some length along y.

For a simple parabolic concentrator, the biconic surface works well, since one can define the y-radius to be 0 (infinite) and the x-conic to be -1. Set the rectangular flag and the extrusion length is defined by the max and min y-apertures. CPC rectangular is obviously intended for this purpose, but it requires a non-zero aperture so, as far as I can tell, one cannot generate “closed bottom” troughs...

But what if the trough profile is something more complex? The help file for the extruded object suggests the extrusion can only be along the z axis, but maybe that is in the local coordinate system, and this limitation can be overcome by a rotation of the object? Then how to define the profile? The help file for the extruded object points to the user defined aperture object, but this only exists in sequential mode. The user defined object seems a bit overkill for this, but maybe the polygon object can be extruded?

Any suggestions very much appreciated!