FBR General Discussion, page-4611

Google "Robot-built wall Zurich" to see an HX competitor for building walls for landscaping, sound barriers, structures on Mars. Pretty amazing, the autonomous robot can take irregularly-shaped rocks or demolition debris, map the number of faces, corners, shape of each rock, and then place it where it fits best. So it doesn't need standardised blocks, but could, for example, grab an odd-shaped boulder weighing a few hundred kg and find a good place to put it. There's a podcast available about it. Making concrete is responsible for about 8% of global CO2 emissions, so this robot is green in that it uses local rock or construction waste.