The Hobby Protection Act prohibits making copies of genuine American articles unless they are marked "COPY." The law does not prohibit making items that are not copies of genuine items, nor does it prohibit making copies of foreign coins (although other fraud laws may apply).

That is how companies can make large 1-ounce silver rounds that look like buffalo nickels without the need to mark them as copies: there was no silver 1-ounce round buffalo nickel.