I love this quote from the thread:
"Assuming just 1psi (2' head, easily achieved with my VAX) over a 2'x2' slab, the suction will be of the order of 500lb. enough to easily raise the heaviest slab."
One atmosphere is 14 psi, and I guess a vacuum cleaner can manage a
1/14th of an atmosphere?The difficulty would be getting a decent seal.