iirc, they can't make one that won't lose or gain mass, it's been suggested that they change the method entirely since you can define it without building an actual little ball
there's also some movement to redefine all of the metric system so it's tied to a single set of formulas
yet nobody cares that this is the same kind of thinking that led the French to adopt a calendar of just ten months and start numbering their years from a totally arbitrary point instead of the scientifically proven method behind such classics as
Batman: Year Onespoiler (click to show/hide)
don't believe Snyder's "Zero Year" anti-science horseshit