The paper describes the construction in some detail. It's an aluminum foam with ceramic spheres embedded in it. They then welded into a thin steel box to give i

The paper describes the construction in some detail. It's an aluminum foam with ceramic spheres embedded in it. They then welded into a thin steel box to give it a uniform surface. If you watch the video, you can see that the grinder gets through the steel box very easily, but the deeper it goes into the aluminum, the faster it is worn away. The grinding wheel is destroyed in just a few seconds, which is pretty impressive. On the other hand I doubt that this will be useful for smaller objects like locks.