2012 Canadian Penny... then in 2013 they are scarce!
Canadian pennies prior to 1997 were approximately 98% copper and 1.75 % zinc. So, a pre-1997 Canadian penny (aside from being illegal to smash in Canada) should give you a decent result after elongating. Note: Do not attempt to elongate a "Loonie" (the non-round coin). It will squish far too short and you will loose part of the design.