Hi Michael, I can't seem to find the source object in the .3dm file you posted. Can you please post one with just the base object and path for the array alone and not just the result of the array?

If the path is planar then I would think you should be able to create offset curves from the path to form boundary curves. You'd offset the path through a vertex of the base object and then move it to the z level of the vertex.

But also like you mention a one rail sweep of edges of the base object should generate some surface pieces as well.

- Michael