3d Printing Counterfeit Coins?

[Compro01]

Why not just move to bills?

Because bills wear out. Coins don't. Even with the new polymer notes we're using up here, a common bill (i.e. not $100s) will last a maximum of about 10 years, whereas I have coins in my pocket that are older than I am.

Additionally, you'd be hard pressed to match the magnetic signature of coins. The RCM invented an interesting multi-ply plating process for counterfeiting resistance (it also makes the coins look nice and shiny), which I doubt you could duplicate with a 3D printer.