Unlike many chemistry projects we post here, making magnetite nanocrystals doesn’t require anything that can’t be found in a local grocery store. All that is required is oil, vinegar, crystal drain opener, and rust. We don’t recognize the specific brand of drain cleaner that they are using, but we’re sure that you could find one with the same ingredients. Magnetite nanocrystals are used to remove arsenic from water. If you are in the USA or most of Europe, that’s not a big concern, but it can’t hurt can it?