I found the basic instructions for this card from the book "Cards that Pop-Up, Flip and Slide" by Michael Jacobs. I tweaked it a little to suit my taste. In the book, the inside 'tag' slides to the right (like the Valentine's card). My vintage card, I decided, should slide upward. I'm including the template, if you would like to try your hand at making one. If you want to see a larger view, just click on the picture and the page should refresh and show you a larger view.
This is the "tag" that will slide out, revealing the message beneath:
I started with a piece that was 8 1/2" x 6 1/2" (so you can make this from an 8 1/2 x 11 piece of cardstock). I don't know if you can tell, but this isn't a simple "window" card. There is a flap that slides behind the panel. It's easier to see this once you've cut out a template. Anyway, you would stamp your sentiment or write your message on that flap. Then the tag slides out, it will reveal the message underneath it. ** Sarah asked me how I cut the cardstock to create the panel. I used an xacto knife and a ruler. ** Thanks for stopping by!