As some of you know, my profession brought me into the orbits of the building and construction trade unions whose skills I came to admire, particularly those of Sheet Metal Workers. Among their skills is making stuff out of stainless sheet metal. I had these shelves made by an apprentice. They are always looking for projects for apprentices, particularly if someone is willing to pay for the materials. Some of the stuff they fabricate are basically building jewelry. Sometimes just stunning. Google their work to see. These shelves are not in that category but they will be quite functional if I can properly attach them.
They will go on an exterior wall and the most convenient locations will be on the windward sides of the house where they will be exposed to the elements. We could put garden and patio tools on them, plants, etc.
This board is literally known throughout the world for its ability to answer the most esoteric of questions and while this question (attaching stuff to Hardi-Plank siding) is not as challenging as how to replace rear tail light lenses on a 1913 Stutz Bearcat, I'd like to get input here on my simple question.