I'm intrigued by the ideas of a company called RedWorks (Source: http://www.fastcompany.com/3058782/redworks-is-building-your-first-home-on-mars)
Their idea is to use software to identify existing geo...sorry, areographic features that could be used to create a habitat, then a large, specialist 3D printer would turn Martian rock into concrete to build the rest. Oh, it will also make the first Martian roads.
And, possibly, roads on Earth, especially in remote areas - the idea of turning whatever dirt you have on hand into a paved road surface is also rather attractive. So is the idea of repairing damaged historic artifacts.