This seems like it could also lead to absurd situations. If a device contained both, would customs pretend it was simultaneously 100% made out of copper and 100% made out of steel and apply both tariffs?
Yes, because it benefits the “here’s how much extra revenue our copper tariffs generate in 2025” sound bites for the Administration to tout (even if they are fabricated numbers based on nonsensical assumptions.)
Furthermore as I know customs, the moment you will start making stuff up in a too brazen way, they will just use Google, search some average price of products and use that instead what you are declaring.
Sometimes it looks like they are getting a cut from amount of tariff they successfully scalp from you.