I recently learned that scrap metal crafted from 2 non-tradables creates non-tradable scrap metal. (And scrap from 2 tradables is tradable)
What would happen if you created scrap metal from 1 tradable and 1 non-tradable?
Any scrap which includes any non-tradable items will in turn be non-tradable, unfortunately.
Things inherit non-tradable properties upwards, so turning an untradable scrap and a tradable scrap into the next tier of metal up will create a non-tradable piece of that metal, and so on, all the way up to non-tradable items.