This is a fascinating development. I’ve written before about the possibilities from “3D printing”. This is a demonstration of a completely solar-powered device that “prints” objects using nothing but sand and sunlight, by sintering sand using a large plastic Fresnel lens.
This may seem like a cute demonstration, but consider some of the implications. For example, turn it over: but the lens and computer on wheels, using solar cells to drive it. It traces out the outline of, say, a building on the sand over many days, automatically. Set it loose, come back in a week or a month, and you have a complete building structure made of fused sand and glass. Shovel the sand out of the inside, and move in. (That not fast enough? Get two machines, or three. Easy to lay out their travel path so they can work in parallel.)
Want to build a Moon colony? Or on Mars? Send the things ahead. When you land at Luna City the first time, Town Hall is already waiting for you.