Swim remembers working in a chem lab a few years ago when there was this hugely accurate. It was mounted on this concrete pilon through 3 stories.. It had a hole drilled in each floor so that neither of them rested on that pilon and made the scale uneven.
It had this 5" x 5" x 3" block of concrete sunk into the ground to make it strong.. Was accurate to 0.000001 grams.. Was a great scale to work with, although hanging your head above the scale when measuring would change the reading.
Now I want a personal version of these scales, but not for the price they want. lol