Aren't most nano-particles suspected of causing cancer? I assume this method would generate fairly small pieces that might make people worry about that.

Also the blender mix would probably (1) make lots of foam and overflow the blender, and (2) stain everything it touches.

CNTs aren't graphine, and I'm not sure that graphine can be easily made into tubes, but it still should give some pause for thought.

Also worth bearing in mind is that, I believe, wherever you make one form of carbon you'll probably end up making other forms too, e.g. buckyballs (C60) and carbon nanotubes have both been found in soot. So even if graphene is safe, I have no idea if this process will produce other potentially unsafe things too. A friend is actually working on looking at the effect carbon nanotubes have on lung epithelial cells, so I know there's interest there.

That said, I imagine you'd find all these products in a standard wood fire too, but then I recall reading that smoke from wood fires is as bad or worse for you as cigarette smoke so perhaps that's little comfort...

Note: I am not a doctor and not an expert in this field either.

The main obstacle I see here (based on this report) is uncertainty about how to separate the material after you've blended it and what exactly you can apply it to without adding lots of expensive lab equipment. One candidate that springs to mind is using it for printing circuits, given graphene's high conductivity.

Random chuncks of graphene thrown toguether, touching in random directions aren't a good conductor at all.

Note: blender wiring can catch fire if they are loaded for extended periods of time (don't underestimate the inertia), but old blenders work fine for at least a few minutes. Lego Technic works great, but only with really solid cross bracing. I recommend building a barricade around it (World Book volumes work nicely).

Edit: I should note that it did work. The rig spun two 10mL test tubes on swing arms at the low(est?) speed setting (which is pretty fast at a 4 inch radius). It seemed to work, but I never did figure out if the scum on top was DNA.