I wish I was a millionaire. I could fulfil my wish of owning replica of IPK that is small cylinder of Platinum-Iridium weighting very very close to kilogram.
Before the standard was changed, I spent a while trying to get one of the prototype silicon sphere kilograms-- slightly misshapen would have been fine-- without success.
International Prototype Kilogram, the mass which used to be the reference standard for the kilogram until it was redefined to be based on fundamental constants a few years ago.
