Guns like this one are actually stupid simple - The complexity and actual power come from the gun powder contained in the bullet. To fire the bullet you just have to hit the back of the casing in the right way with enough force. All the gun like this one needs is some type of firing pin to strike the casing of the bullet - And reading the article it seems that part isn't actually 3D printed. A revolver is slightly more complicated then a single shot, but really it's just a single-shot with multiple 'barrel inserts', in a way.
A vacuum cleaner design is unlikely to be a thing within the foreseeable future - The complexity is actually much higher then the gun here because you need a motor, which probably can't be 3D printed and wouldn't be as easy for someone to get a hold of.
A vacuum cleaner design is unlikely to be a thing within the foreseeable future - The complexity is actually much higher then the gun here because you need a motor, which probably can't be 3D printed and wouldn't be as easy for someone to get a hold of.