Just stop making pennies and nickels. We hardly use them. Most vending machines won’t take them and pay phones are a thing of the past. Trade up for dollar and 5 dollar coins since coin is more durable than paper money and use cheaper material across the board. All the world currencies are fiat money now so it literally doesn’t matter what it’s made of as long as it’s durable. It could be recycled plastic for all that it matters.