I've been Counter striking pennies for years !
Despite what a few claim it's not illegal !
As a matter of policy, the Mint does not promote coloring, plating or altering U.S. coinage: however, there are no sanctions against such activity absent fraudulent intent. ... Stamping words or letters on a coin is perfectly legal.
I just got a roll of Lincoln Rail Splitter pennies.
The results are better than I had hoped for !