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I think with the weight of the tanks, the stacked pipes will start to slide. Maybe with a rubber mat under it won't but I think they might tip or shift on a regular not so gentle turn. I'm not sure. I was thinking that though. Also I just realized 8" means can't do the 130 tank.
Very creative, I especially like how in a pinch you can flip the tank holder upside down and use the cutting board to chop away. Plus it has a convenient handle, I think you need a patent lawyer.