The guys from Waterjet Channel took a request from a Minecraft fan who wanted to see them cut an obsidian cube, even supplying the obsidian. They also made some super-thin batarangs that could almost be used as sunglass lenses. Read the rest
Andy from How To Make Everything went out in the Utah desert, gathered up volcanic glass, then through trial and error learned how to make an Aztec-style edge weapon.
The episode includes an interesting history lesson from anthropologist Gilbert Tostevin at University of Minnesota, who shows Andy how Aztecs used a haft embedded with smaller obsidian pieces to make formidable weapons.