12 sided is "twelve rode rims" 

A coin is one plus one sides and rim as rim is the unique of the account of the twelve as twelve sides asks two selectively express the 365 day year division as a twelve month year, for banking and taxes, possibly to eliminate the thirteen month twenty eight day four week even sided mystical door of even flow. as it will be easer to see the thirteen rim coin as a day is missing for the year.  so the coin is to remind every good man this is a mystical thing as life is a coin for the watch, spec-tic-ally I the 2 dollar coin as also is implied.