Solar Sintering is a technology that is particularly useful for crafting objects and at the large scale, structures, in dry environments using only sunlight and sand or regolith (rock dust).
Solar energy is simply focused on a small volume of bedded granular material to heat the material to a point where melt occurs and either the grains are bonded at the surface by micro melt grain welding or the whole grain melts and forms a crystal.
Markus Kayser - Solar Sinter Project
Markus Kayser - Solar Sinter Project from Markus Kayser on Vimeo.
Markus Kayser's creations are rough with some non sintered sand bonded to the surface. In theory this can be fixed by quickly passing the work though the focal point with the plain of the focal point normal to the internal or external surface. A sand blaster could also smooth the works. Markus is an artist, his works will sell better if its clear how they are made. So perfectly smooth is not optimal for him. Nor is it optimal on all sintered applications particularly external bricks. A rough surface casts complex shadow's on its self when the sun is at an angle to the face this cools the face and reduces glare.
The advantages are that you don't need water or cement to make solid objects in the desert. The resulting ceramic is one of the strongest known and a refractory material. It endures for millennia and is water proof if crafted properly. The process is not fast; you will need more than one unit to be productive. However the Fresnel lenses are cheap and all the other parts can be built using the existing OS village technology. This technology will not work well above 40 degrees latitude but near the equator, at high altitudes and in most of the worlds sandy deserts it is a game changer.
For efficient village industrial scale production of quartz glass materials, particularly tiles and blocks, several solar sinter units along a conveyor belt would be optimal reducing man handling of hot quartz. Each lens does one layer or one melt width. In some cases three dimensions are not needed I.E. tiles.
Shade in the desert is all important. Deserts are not just dry because they get little rainfall. Dew fall in the cold nights can often be high. They are dry because evaporation rates exceed the little precipitation they get. Creating shade creates oasis's. With shade water can be accumulated and stored. Plants can grow well if they are shaded in the hottest part of the day, often the afternoon not midday.
There has also been work on solar sintering Luna regolith (moon dust or simulated moon dust.) Designs are generally much larger with one design using a mobile mirror array to sinter a road surface! Others are designed to print structural elements. On the moon the light level is several times higher, Luna regolith has a lower melting point and there is no atmosphere to carry away heat so its a much more powerful technology on the moon.  and 
With this technology its possible for a tropical or desert village to make tiles, refractory bricks, bowls and pots, quartz structural elements, rods, blocks, and mouldings. It could even, with a little more work be possible to make linear bearing surfaces, metal casting moulds and fibre glass like sheets with or without perforations.
Markus' process should work on some other material including small grain gravels, scrap glass, and Calcium carbonates making lime or flint depending on the pressure. It may also be used to cook ores, cracking them, prior to smelting. Milled metal powders and scrap chips should tested both in atmosphere and in a inert or reducing gas to see if the process works for them. It may be possible print (weld) the shape and then pack in sand and heat in a furnace to finalise the form.
Proper care should be taken: shade for the workers, protective gloves and tongs, protective goggles or a welders mask may be wise. Markus made his work in the desert look harder than it was to add a little drama.