This one (which unfortunately arrived with a broken button, which I will try to find a match for in my stash) is really good fun - the card started with just the background and pocket, which are both paper. I added the metal charm on a ribbon and the third player added the buttons.
Here's another card progression - the background arrived to me - a torn edged piece of paper printed with sheet music, mounted on a black card.
I added some birds, punched out of music, to go with the theme. And I like birds.
And here it is, finished off!
This one, I'll deconstruct - above is the finished item.
Here's what it looked like when I finished
And here's how it was when I received it - definitely fun to watch them change...