After thinking about the physics of this type of contraption, my conclusion is generally speaking, with some narrow possible semi-safe uses, I don't see much safety or overall utility for this setup. I'm going to pass, since the effectiveness and safety of this thing requires perfect balance and a perfectly flat floor with zero slope in any direction, in a best case situation, and even in that situation the design still doesn't make a whole lot of sense lifting vehicles. At least not for a driveway duffer like me.