HI guys, the 2 bottles interconnected by tube idea for use as a level is no con- in fact it is one of the most if not the most acurate ways of finding level & certainly more acurate than a zip laser, zips are typically 3% out. I actually used a slightly more sophisticated version of this method 45 years ago when my grandfather ( a masterbuilder, carpenter & cabinetmaker built his own house) he told me it was more acurate over a longer distance than a level.
Of course you will have a problem proving it to Fletchers builders but then they would probably have never seen one let alone used one.
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