You can export coins, however, there is a cap and it is quite small. $5000 worth of coins for collecting purposes is allowed, or something like that.
relevant law: United States Mint Moves to Limit Exportation & Melting of Coins http://www.usmint.gov/pressroom/?flash=yes&action=press_release&ID=724
No, its illegal to melt them, period. http://www.usmint.gov/pressroom/index.cfm?action=press_release&ID=724 If you have evidence to the contrary post it. Those machines that alter coins are not illegal: http://www.ustreas.gov/education/faq/coins/portraits.shtml#q13 "Question: Is it illegal to damage or deface coins? Answer: Section 331 of Title 18 of the United States code provides criminal penalties for anyone who âfraudulently alters, defaces, mutilates impairs, diminishes, falsifies, scales, or lightens any of the coins coined at the Mints of the United States.â This statute means that you may be violating the law if you change the appearance of the coin and fraudulently represent it to be other than the altered coin that it is. As a matter of policy, the U.S. Mint does not promote coloring, plating or altering U.S. coinage: however, there are no sanctions against such activity absent fraudulent intent." Note that US mint rule also addresses the idea of exporting them and melting them outside the US - also illegal.
Does anyone else see the problem when a countries coins are worth more than face value and the dollar keeps going down in value? The government spends $1.26 million to make $1 million of nickels. Every year the government generally makes a little more than a billion nickels. So this year its possible that the government will lose 12 million dollars making nickels. Oh for those of you that thought i was serious about melting nickels im not. I'm well aware of the law that came out in 2006 that even makes it illegal to transport nickels outside the US, let alone melt them down. But like I said...on a small scale its legal, but in the law books they dont define what constitutes large or small scale. Large scale might be a couple hundred dollars of nickels. Who knows.
Sorry...i just reread the dec 14, 2006 rules. It was not illegal to melt coins before that date, but yes...now it is. Apparently though you can smash pennies as long as you are not attempting to commit fraud.