Isn't ice the perfect engineering material on mars, an environment mostly below the freezing point?
It is easy to procure, easy to manipulate in its solid form and easy to melt for casting, "welding", 3D printing. It is literally the best material for shielding space radiation and also happens to be transparent.

I mostly heard about sub surface colonies with people living without sunlight or even windows. Why is nobody talking about ice cities on mars? Habitats would still need an inner layer providing insulation and stuff, but that's little mass if you already have a giant ice building that's air tight, see through, and protecting from space radiation and meteoroids. You could also do other stuff like building big lenses.

Am I missing something or why is there no ice hype around the mars colony?