I have a number of features that are used to create a 3d loft of a weldment profile, twisting as necessary to remain normal to its parent surface.

I have attempted to group these into a library Part, but the ruled surfaces (that are required to create the guide curves that create a fair loft) are not included in my Library Part.

Is there something obvious I'm missing here?  Should this work as a Library Part, or have I crossed over into the "API" side? 

Thanks for having a look at this.