copper pennies or copper bars. I know it‘s illegal to melt pennies but if we ever get rid of the penny, the laws about pennies will change.
Bad idea. Copper is a good metal if you can find a junk yard that will let you pick it up, then melt it down into bars. Many older houses have copper wiring. If they are being torn down, that is another good place to get some.
Now see - that's a novel investing idea. Stockpile pre-1982 pennies that you can get for 1 cent each and then lobby to get rid of the penny and the laws about melting them down. When th laws change,sell your pennies for scrap and you can probably double your money. Problems: a) The transactions costs on selling copper are pretty high b) It takes lots of work to separate copper pennies from zinc ones (but I bet I could make a machine) c) Nobody seems interested in getting rid of pennies anytime soon. Remember they talked about getting rid of pennies in the '70's and they still haven't. d) You have to store unbelievable amounts of copper to have a significant amount of money e) Copper prices are stagnant to down and as an industrial metal, recession (which seems likely to me) will kill the price of copper. Why don't you start learning about equity analysis or bond analysis and get some real investment skill instead of worrying about small quantities of physical metals? If you really like metals, start figuring out how you can successfully trade the LME.
My advice would be pennies, but not for the reasons you are considering. Melting them down involves at lot more complications than legal considerations. I would 'buy' $100 in pennies and sift through them looking for relatively rare dates in good condition and then sell them for their numismatic value. Trade the pennies back to the bank for a new batch and keep up the process.